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

Convert the PM documents to ReST, in order to allow them to
build with Sphinx.

The conversion is actually:
  - add blank lines and indentation 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: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>

kernel/power/Kconfig

@@ -65,7 +65,7 @@ config HIBERNATION
 	  need to run mkswap against the swap partition used for the suspend.
 
 	  It also works with swap files to a limited extent (for details see
-	  <file:Documentation/power/swsusp-and-swap-files.txt>).
+	  <file:Documentation/power/swsusp-and-swap-files.rst>).
 
 	  Right now you may boot without resuming and resume later but in the
 	  meantime you cannot use the swap partition(s)/file(s) involved in
@@ -74,7 +74,7 @@ config HIBERNATION
 	  MOUNT any journaled filesystems mounted before the suspend or they
 	  will get corrupted in a nasty way.
 
-	  For more information take a look at <file:Documentation/power/swsusp.txt>.
+	  For more information take a look at <file:Documentation/power/swsusp.rst>.
 
 config ARCH_SAVE_PAGE_KEYS
 	bool
@@ -255,7 +255,7 @@ config APM_EMULATION
 	  notification of APM "events" (e.g. battery status change).
 
 	  In order to use APM, you will need supporting software. For location
-	  and more information, read <file:Documentation/power/apm-acpi.txt>
+	  and more information, read <file:Documentation/power/apm-acpi.rst>
 	  and the Battery Powered Linux mini-HOWTO, available from
 	  <http://www.tldp.org/docs.html#howto>.