docs: move scripts/documentation-file-ref-check to tools/docs

Add this script to the growing collection of documentation tools.

Reviewed-by: Mauro Carvalho Chehab <[e-mail]>
Acked-by: Jani Nikula <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/Makefile

···
 ifneq ($(MAKECMDGOALS),cleandocs)
 # Check for broken documentation file references
 ifeq ($(CONFIG_WARN_MISSING_DOCUMENTS),y)
-$(shell $(srctree)/scripts/documentation-file-ref-check --warn)
+$(shell $(srctree)/tools/docs/documentation-file-ref-check --warn)
 endif
 
 # Check for broken ABI files
···
 	@tools/docs/gen-redirects.py --output $(BUILDDIR) < $<
 
 refcheckdocs:
-	$(Q)cd $(srctree);scripts/documentation-file-ref-check
+	$(Q)cd $(srctree); tools/docs/documentation-file-ref-check
 
 cleandocs:
 	$(Q)rm -rf $(BUILDDIR)

MAINTAINERS

···
 P:	Documentation/doc-guide/maintainer-profile.rst
 T:	git git://git.lwn.net/linux.git docs-next
 F:	Documentation/
-F:	scripts/documentation-file-ref-check
 F:	scripts/get_abi.py
 F:	scripts/kernel-doc*
 F:	scripts/lib/abi/*
···
 L:	[e-mail]
 S:	Maintained
 F:	Documentation/sphinx/parse-headers.pl
-F:	scripts/documentation-file-ref-check
 F:	tools/docs/sphinx-pre-install
 
 DOCUMENTATION/ITALIAN

scripts/documentation-file-ref-check tools/docs/documentation-file-ref-check

···
 );
 
 my $scriptname = $0;
-$scriptname =~ s,.*/([^/]+/),$1,;
+$scriptname =~ s,tools/docs/([^/]+/),$1,;
 
 # Parse arguments
 my $help = 0;

tools/docs/sphinx-pre-install

···
         Right now, we still need Perl for doc build, as it is required
         by some tools called at docs or kernel build time, like:
 
-            scripts/documentation-file-ref-check
+            tools/docs/documentation-file-ref-check
 
         Also, checkpatch is on Perl.
         """