Help: Add documentation style section headers to cmake-developer.7

Give the style guides titles instead of numbers so we can link to them.

Help/manual/cmake-developer.7.rst

@@ -465,11 +465,12 @@ with an explicit target.
 Style
 -----
 
-1)
+Style: Command Signatures
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
 Command signatures should be marked up as plain literal blocks, not as
 cmake ``code-blocks``.
 
-2)
 Signatures are separated from preceding content by a horizontal
 line. That is, use:
 
@@ -485,30 +486,40 @@ Style
 
   This signature is used for ...
 
-3)
+Style: Boolean Constants
+^^^^^^^^^^^^^^^^^^^^^^^^
+
 Use "``OFF``" and "``ON``" for boolean values which can be modified by
 the user, such as :prop_tgt:`POSITION_INDEPENDENT_CODE`. Such properties
 may be "enabled" and "disabled". Use "``True``" and "``False``" for
 inherent values which can't be modified after being set, such as the
 :prop_tgt:`IMPORTED` property of a build target.
 
-4)
+Style: Whitespace
+^^^^^^^^^^^^^^^^^
+
 Use two spaces for indentation.  Use two spaces between sentences in
 prose.
 
-5)
+Style: Starting Literal Blocks
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 Prefer to mark the start of literal blocks with ``::`` at the end of
 the preceding paragraph. In cases where the following block gets
 a ``code-block`` marker, put a single ``:`` at the end of the preceding
 paragraph.
 
-6)
+Style: Line Length
+^^^^^^^^^^^^^^^^^^
+
 Prefer to restrict the width of lines to 75-80 columns.  This is not a
 hard restriction, but writing new paragraphs wrapped at 75 columns
 allows space for adding minor content without significant re-wrapping of
 content.
 
-7)
+Style: Document Self-References
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 Mark up self-references with  ``inline-literal`` syntax. For example,
 within the add_executable command documentation, use
 
@@ -524,13 +535,17 @@ Style
 
 which is used elsewhere.
 
-8)
+Style: Linkable References
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 Mark up all other linkable references as links, including repeats. An
 alternative, which is used by wikipedia (`<http://en.wikipedia.org/wiki/WP:REPEATLINK>`_),
 is to link to a reference only once per article. That style is not used
 in CMake documentation.
 
-9)
+Style: Technical Terms
+^^^^^^^^^^^^^^^^^^^^^^
+
 Mark up references to keywords in signatures, file names, and other
 technical terms with ``inline-literl`` syntax, for example:
 
@@ -540,8 +555,9 @@ Style
   :prop_tgt:`WIN32_EXECUTABLE` target property is enabled. That command
   creates the file ``<name>.exe`` on Windows.
 
+Style: Referencing Concepts
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-10)
 If referring to a concept which corresponds to a property, and that
 concept is described in a high-level manual, prefer to link to the
 manual section instead of the property. For example:
@@ -575,7 +591,6 @@ Style
 (``IMPORTED``), a target property (:prop_tgt:`IMPORTED`), or a
 concept (:ref:`Imported Targets`).
 
-11)
 Where a property, command or variable is related conceptually to others,
 by for example, being related to the buildsystem description, generator
 expressions or Qt, each relevant property, command or variable should
@@ -583,7 +598,9 @@ Style
 particular information relating to the command should be in the
 documentation of the command.
 
-12)
+Style: Section Titles
+^^^^^^^^^^^^^^^^^^^^^
+
 When marking section titles, make the section decoration line as long as
 the title text.  Use only a line below the title, not above. For
 example:
@@ -595,7 +612,9 @@ Style
 
 Capitalize the first letter of each non-minor word in the title.
 
-13)
+Style: Referencing CMake Domain Objects
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 When referring to properties, variables, commands etc, prefer to link
 to the target object and follow that with the type of object it is.
 For example:
@@ -617,16 +636,19 @@ Style
 
   If policy :prop_tgt:`CMP0022` is set to ``NEW`` the behavior is ...
 
-14)
+Style: Command Signature Markup
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 Signatures of commands should wrap optional parts with square brackets,
 and should mark list of optional arguments with an ellipsis (``...``).
 Elements of the signature which are specified by the user should be
 specified with angle brackets, and may be referred to in prose using
 ``inline-literal`` syntax.
 
-15)
-  Use American English spellings in prose.
+Style: Prose
+^^^^^^^^^^^^
 
+Use American English spellings in prose.
 
 Modules
 =======