kernel-doc: Update "cross-referencing from rST" section to use automarkup

Update text and examples in the "Cross-referencing from
reStructuredText" section to reflect that no additional syntax is needed
anymore.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@protonmail.com>
Link: https://lore.kernel.org/r/20200903005747.3900333-3-nfraprado@protonmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/doc-guide/kernel-doc.rst

@@ -387,22 +387,23 @@ Domain`_ references.
 Cross-referencing from reStructuredText
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-To cross-reference the functions and types defined in the kernel-doc comments
-from reStructuredText documents, please use the `Sphinx C Domain`_
-references. For example::
+No additional syntax is needed to cross-reference the functions and types
+defined in the kernel-doc comments from reStructuredText documents.
+Just end function names with ``()`` and write ``struct``, ``union``, ``enum``
+or ``typedef`` before types.
+For example::
 
-  See function :c:func:`foo` and struct/union/enum/typedef :c:type:`bar`.
+  See foo().
+  See struct foo.
+  See union bar.
+  See enum baz.
+  See typedef meh.
 
-While the type reference works with just the type name, without the
-struct/union/enum/typedef part in front, you may want to use::
+However, if you want custom text in the cross-reference link, that can be done
+through the following syntax::
 
-  See :c:type:`struct foo <foo>`.
-  See :c:type:`union bar <bar>`.
-  See :c:type:`enum baz <baz>`.
-  See :c:type:`typedef meh <meh>`.
-
-This will produce prettier links, and is in line with how kernel-doc does the
-cross-references.
+  See :c:func:`my custom link text for function foo <foo>`.
+  See :c:type:`my custom link text for struct bar <bar>`.
 
 For further details, please refer to the `Sphinx C Domain`_ documentation.