docs: connector: convert to ReST and rename to connector.rst

As it has some function definitions, move them to connector.h.

The remaining 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>

drivers/w1/Kconfig

@@ -19,7 +19,7 @@ config W1_CON
 	default y
 	---help---
 	  This allows to communicate with userspace using connector. For more
-	  information see <file:Documentation/connector/connector.txt>.
+	  information see <file:Documentation/connector/connector.rst>.
 	  There are three types of messages between w1 core and userspace:
 	  1. Events. They are generated each time new master or slave device found
 		either due to automatic or requested search.