docs: add links for single & multipage views

Signed-off-by: oppiliappan <[e-mail]>

docs/mode.html

···
+<a class="px-4 py-2 mt-8 block text-center w-full rounded-sm shadow-sm border border-gray-200 dark:border-gray-700 no-underline hover:no-underline" href="$if(single-page)$/$else$/single-page.html$endif$">
+  $if(single-page)$View as multi-page$else$View as single-page$endif$
+</a>

docs/template.html

···
           $if(toc-title)$$toc-title$$else$Table of Contents$endif$
         </button>
         ${ table-of-contents:toc.html() }
+        ${ single-page:mode.html() }
       </div>
 
 
···
         <h2 id="$idprefix$toc-title" class="text-lg font-semibold mb-4 text-gray-900">$toc-title$</h2>
         $endif$
         ${ table-of-contents:toc.html() }
+        ${ single-page:mode.html() }
       </nav>
     $endif$
 

nix/pkgs/docs.nix

···
   # icons
   cp -rf ${lucide-src}/*.svg working/
 
-  # content
+  # content - chunked
   ${pandoc}/bin/pandoc ${src}/docs/DOCS.md \
     -o $out/ \
     -t chunkedhtml \
     --variable toc \
+    --variable-json single-page=false \
     --toc-depth=2 \
     --css=stylesheet.css \
     --chunk-template="%i.html" \
+    --highlight-style=working/highlight.theme \
+    --template=working/template.html
+
+  # content - single page
+  ${pandoc}/bin/pandoc ${src}/docs/DOCS.md \
+    -o $out/single-page.html \
+    --toc \
+    --variable toc \
+    --variable single-page \
+    --toc-depth=2 \
+    --css=stylesheet.css \
     --highlight-style=working/highlight.theme \
     --template=working/template.html