nixos/doc/*: fix indentation

nixos/doc/manual/configuration/gpu-accel.xml

···
       <title>AMD</title>
 
       <para>
-	Modern AMD <link
-	xlink:href="https://en.wikipedia.org/wiki/Graphics_Core_Next">Graphics
-	Core Next</link> (GCN) GPUs are supported through the
-	<package>rocm-opencl-icd</package> package. Adding this package to
-	<xref linkend="opt-hardware.opengl.extraPackages"/> enables OpenCL
-	support:
+       Modern AMD <link
+       xlink:href="https://en.wikipedia.org/wiki/Graphics_Core_Next">Graphics
+       Core Next</link> (GCN) GPUs are supported through the
+       <package>rocm-opencl-icd</package> package. Adding this package to
+       <xref linkend="opt-hardware.opengl.extraPackages"/> enables OpenCL
+       support:
 
-	<programlisting><xref linkend="opt-hardware.opengl.extraPackages"/> = [
-  rocm-opencl-icd
-];</programlisting>
+       <programlisting><xref linkend="opt-hardware.opengl.extraPackages"/> = [
+         rocm-opencl-icd
+       ];</programlisting>
       </para>
     </section>
 
···
        support. For example, for Gen8 and later GPUs, the following
        configuration can be used:
 
-	      <programlisting><xref linkend="opt-hardware.opengl.extraPackages"/> = [
-  intel-compute-runtime
-];</programlisting>
+      <programlisting><xref linkend="opt-hardware.opengl.extraPackages"/> = [
+        intel-compute-runtime
+      ];</programlisting>
 
       </para>
     </section>
···
       <title>AMD</title>
 
       <para>
-	Modern AMD <link
-	xlink:href="https://en.wikipedia.org/wiki/Graphics_Core_Next">Graphics
-	Core Next</link> (GCN) GPUs are supported through either radv, which is
-	part of <package>mesa</package>, or the <package>amdvlk</package> package.
-	Adding the <package>amdvlk</package> package to
-	<xref linkend="opt-hardware.opengl.extraPackages"/> makes both drivers
-	available for applications and lets them choose. A specific driver can
-	be forced as follows:
+       Modern AMD <link
+       xlink:href="https://en.wikipedia.org/wiki/Graphics_Core_Next">Graphics
+       Core Next</link> (GCN) GPUs are supported through either radv, which is
+       part of <package>mesa</package>, or the <package>amdvlk</package> package.
+       Adding the <package>amdvlk</package> package to
+       <xref linkend="opt-hardware.opengl.extraPackages"/> makes both drivers
+       available for applications and lets them choose. A specific driver can
+       be forced as follows:
 
-	<programlisting><xref linkend="opt-hardware.opengl.extraPackages"/> = [
-  pkgs.<package>amdvlk</package>
-];
+       <programlisting><xref linkend="opt-hardware.opengl.extraPackages"/> = [
+         pkgs.<package>amdvlk</package>
+       ];
 
-# To enable Vulkan support for 32-bit applications, also add:
-<xref linkend="opt-hardware.opengl.extraPackages32"/> = [
-  pkgs.driversi686Linux.<package>amdvlk</package>
-];
+       # To enable Vulkan support for 32-bit applications, also add:
+       <xref linkend="opt-hardware.opengl.extraPackages32"/> = [
+         pkgs.driversi686Linux.<package>amdvlk</package>
+       ];
 
-# For amdvlk
-<xref linkend="opt-environment.variables"/>.VK_ICD_FILENAMES =
-   "/run/opengl-driver/share/vulkan/icd.d/amd_icd64.json";
-# For radv
-<xref linkend="opt-environment.variables"/>.VK_ICD_FILENAMES =
-  "/run/opengl-driver/share/vulkan/icd.d/radeon_icd.x86_64.json";
-</programlisting>
+       # For amdvlk
+       <xref linkend="opt-environment.variables"/>.VK_ICD_FILENAMES =
+          "/run/opengl-driver/share/vulkan/icd.d/amd_icd64.json";
+       # For radv
+       <xref linkend="opt-environment.variables"/>.VK_ICD_FILENAMES =
+         "/run/opengl-driver/share/vulkan/icd.d/radeon_icd.x86_64.json";
+       </programlisting>
       </para>
     </section>
   </section>

nixos/doc/manual/release-notes/rl-2009.xml

···
      <para>
       Agda has been heavily reworked.
       <itemizedlist>
-	<listitem>
-	  <para>
-	    <literal>agda.mkDerivation</literal> has been heavily changed and
-	    is now located at <package>agdaPackages.mkDerivation</package>.
-	  </para>
-	</listitem>
-	<listitem>
-	  <para>
-	    New top-level packages <package>agda</package> and
-	    <literal>agda.withPackages</literal> have been added, the second
-	    of which sets up agda with access to chosen libraries.
-	  </para>
-	</listitem>
-	<listitem>
-	  <para>
-	    All agda libraries now live under
-	    <literal>agdaPackages</literal>.
-	  </para>
-	</listitem>
-	<listitem>
-	  <para>
-	    Many broken libraries have been removed.
-	  </para>
-	</listitem>
+       <listitem>
+         <para>
+           <literal>agda.mkDerivation</literal> has been heavily changed and
+           is now located at <package>agdaPackages.mkDerivation</package>.
+         </para>
+       </listitem>
+       <listitem>
+         <para>
+           New top-level packages <package>agda</package> and
+           <literal>agda.withPackages</literal> have been added, the second
+           of which sets up agda with access to chosen libraries.
+         </para>
+       </listitem>
+       <listitem>
+         <para>
+           All agda libraries now live under
+           <literal>agdaPackages</literal>.
+         </para>
+       </listitem>
+       <listitem>
+         <para>
+           Many broken libraries have been removed.
+         </para>
+       </listitem>
       </itemizedlist>
       See the <link
       xlink:href="https://nixos.org/nixpkgs/manual/#agda">new

nixos/doc/varlistentry-fixer.rb

···
 include REXML
 
 if ARGV.length < 1 then
-	$stderr.puts "Needs a filename."
-	exit 1
+  $stderr.puts "Needs a filename."
+  exit 1
 end
 
 filename = ARGV.shift
···
 # Generates: --optionnamevalue
 #                   ^^  ^^
 doc.elements.each("//varlistentry/term") do |term|
-	["varname", "function", "option", "replaceable"].each do |prev_name|
-		term.elements.each(prev_name) do |el|
-			if el.next_element and
-					el.next_element.name == "replaceable" and
-					el.next_sibling_node.class == Element
-				then
-				$touched = true
-				term.insert_after(el, Text.new(" "))
-			end
-		end
-	end
+  ["varname", "function", "option", "replaceable"].each do |prev_name|
+    term.elements.each(prev_name) do |el|
+      if el.next_element and
+          el.next_element.name == "replaceable" and
+          el.next_sibling_node.class == Element
+        then
+        $touched = true
+        term.insert_after(el, Text.new(" "))
+      end
+    end
+  end
 end
 
 
···
 # Generates: -Ipath
 #             ^^
 doc.elements.each("//cmdsynopsis/arg") do |term|
-	["option", "replaceable"].each do |prev_name|
-		term.elements.each(prev_name) do |el|
-			if el.next_element and
-				el.next_element.name == "replaceable" and
-				el.next_sibling_node.class == Element
-			then
-				$touched = true
-				term.insert_after(el, Text.new(" "))
-			end
-		end
-	end
+  ["option", "replaceable"].each do |prev_name|
+    term.elements.each(prev_name) do |el|
+      if el.next_element and
+        el.next_element.name == "replaceable" and
+        el.next_sibling_node.class == Element
+      then
+        $touched = true
+        term.insert_after(el, Text.new(" "))
+      end
+    end
+  end
 end
 
 #  <cmdsynopsis>
···
 # Generates: [{--profile-name | -p }name]
 #                                   ^^^^
 doc.elements.each("//cmdsynopsis/arg") do |term|
-	["group"].each do |prev_name|
-		term.elements.each(prev_name) do |el|
-			if el.next_element and
-				el.next_element.name == "replaceable" and
-				el.next_sibling_node.class == Element
-			then
-				$touched = true
-				term.insert_after(el, Text.new(" "))
-			end
-		end
-	end
+  ["group"].each do |prev_name|
+    term.elements.each(prev_name) do |el|
+      if el.next_element and
+        el.next_element.name == "replaceable" and
+        el.next_sibling_node.class == Element
+      then
+        $touched = true
+        term.insert_after(el, Text.new(" "))
+      end
+    end
+  end
 end
 
 
 if $touched then
-	doc.context[:attribute_quote] = :quote
-	doc.write(output: File.open(filename, "w"))
+  doc.context[:attribute_quote] = :quote
+  doc.write(output: File.open(filename, "w"))
 end