docs: target: convert docs to ReST and rename to *.rst

Convert the TCM docs to ReST format and add them to the
bookset.

This has a mix of userspace-faced and Kernelspace faced
docs. Still, it sounds a better candidate to be added at
the kernel API set of docs.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/scripts/documentation-file-ref-check b/scripts/documentation-file-ref-check
index 440227b..a4139a5 100755
--- a/scripts/documentation-file-ref-check
+++ b/scripts/documentation-file-ref-check
@@ -124,7 +124,7 @@
 		# Remove sched-pelt false-positive
 		next if ($fulref =~ m,^Documentation/scheduler/sched-pelt$,);
 
-		# Discard some build examples from Documentation/target/tcm_mod_builder.txt
+		# Discard some build examples from Documentation/target/tcm_mod_builder.rst
 		next if ($fulref =~ m,mnt/sdb/lio-core-2.6.git/Documentation/target,);
 
 		# Check if exists, evaluating wildcards