docs: kernel-doc.rst: improve structs chapter

There is a mess on this chapter: it suggests that even
enums and unions should be documented with "struct". That's
not the way it should be ;-)

Fix it and move it to happen earlier.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/doc-guide/kernel-doc.rst

@@ -258,6 +258,30 @@ named ``Return``.
      as a new section heading, with probably won't produce the desired
      effect.
 
+Structure, union, and enumeration documentation
+-----------------------------------------------
+
+The general format of a struct, union, and enum kernel-doc comment is::
+
+  /**
+   * struct struct_name - Brief description.
+   * @argument: Description of member member_name.
+   *
+   * Description of the structure.
+   */
+
+On the above, ``struct`` is used to mean structs. You can also use ``union``
+and ``enum``  to describe unions and enums. ``argument`` is used
+to mean struct and union member names as well as enumerations in an enum.
+
+The brief description following the structure name may span multiple lines, and
+ends with a member description, a blank comment line, or the end of the
+comment block.
+
+The kernel-doc data structure comments describe each member of the structure,
+in order, with the member descriptions.
+
+
 
 Highlights and cross-references
 -------------------------------
@@ -331,30 +355,6 @@ cross-references.
 For further details, please refer to the `Sphinx C Domain`_ documentation.
 
 
-Structure, union, and enumeration documentation
------------------------------------------------
-
-The general format of a struct, union, and enum kernel-doc comment is::
-
-  /**
-   * struct struct_name - Brief description.
-   * @member_name: Description of member member_name.
-   *
-   * Description of the structure.
-   */
-
-Below, "struct" is used to mean structs, unions and enums, and "member" is used
-to mean struct and union members as well as enumerations in an enum.
-
-The brief description following the structure name may span multiple lines, and
-ends with a ``@member:`` description, a blank comment line, or the end of the
-comment block.
-
-The kernel-doc data structure comments describe each member of the structure, in
-order, with the ``@member:`` descriptions. The ``@member:`` descriptions must
-begin on the very next line following the opening brief function description
-line, with no intervening blank comment lines. The ``@member:`` descriptions may
-span multiple lines. The continuation lines may contain indentation.
 
 In-line member documentation comments
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~