Help: Add .. versionadded directives to commands documentation

This change ony concerns directives that appear in the document body.

The guidelines for inserting version directives:

 * Baseline version is CMake 3.0, i.e. directives start at 3.1.
 * Always use `.. versionadded::` directive, avoid ad-hoc version
   references. Exception: policy pages.
 * For new command signatures, put `versionadded` on a separate line
   after the signature.
 * For a group of new signatures in a new document section,
   a single version note at the beginning of the section is sufficient.
 * For new options, put `versionadded` on a separate line before
   option description.
 * If all the option descriptions in the list are short one-liners,
   it's fine to put `versionadded` on the same line as the description.
 * If multiple option descriptions in close proximity would have
   the same ..versionadded directive, consider adding a single
   directive after the list, mentioning all added options.
 * For compact value lists and sub-option lists, put a single
  `versionadded` directive after the list mentioning all additions.
 * When a change is described in a single paragraph, put
   `versionadded` into that paragraph.
 * When only part of the paragraph has changed, separate the changed
   part if it doesn't break the flow. Otherwise, write a follow-up
   clarification paragraph and apply version directive to that.
 * When multiple version directives are close by, order earlier
   additions before later additions.
 * Indent related lists and code blocks to include them in the scope
   of `versionadded` directive.

Issue: #19715

Help/command/add_executable.rst

@@ -17,13 +17,21 @@ Normal Executables
                  [source1] [source2 ...])
 
 Adds an executable target called ``<name>`` to be built from the source
-files listed in the command invocation.  (The source files can be omitted
-here if they are added later using :command:`target_sources`.)  The
+files listed in the command invocation.  The
 ``<name>`` corresponds to the logical target name and must be globally
 unique within a project.  The actual file name of the executable built is
 constructed based on conventions of the native platform (such as
 ``<name>.exe`` or just ``<name>``).
 
+.. versionadded:: 3.1
+  Source arguments to ``add_executable`` may use "generator expressions" with
+  the syntax ``$<...>``.  See the :manual:`cmake-generator-expressions(7)`
+  manual for available expressions.
+
+.. versionadded:: 3.11
+  The source files can be omitted if they are added later using
+  :command:`target_sources`.
+
 By default the executable file will be created in the build tree
 directory corresponding to the source tree directory in which the
 command was invoked.  See documentation of the
@@ -43,10 +51,8 @@ If ``EXCLUDE_FROM_ALL`` is given the corresponding property will be set on
 the created target.  See documentation of the :prop_tgt:`EXCLUDE_FROM_ALL`
 target property for details.
 
-Source arguments to ``add_executable`` may use "generator expressions" with
-the syntax ``$<...>``.  See the :manual:`cmake-generator-expressions(7)`
-manual for available expressions.  See the :manual:`cmake-buildsystem(7)`
-manual for more on defining buildsystem properties.
+See the :manual:`cmake-buildsystem(7)` manual for more on defining
+buildsystem properties.
 
 See also :prop_sf:`HEADER_FILE_ONLY` on what to do if some sources are
 pre-processed, and you want to have the original sources reachable from
@@ -85,10 +91,14 @@ be used to refer to ``<target>`` in subsequent commands.  The ``<name>``
 does not appear in the generated buildsystem as a make target.  The
 ``<target>`` may not be an ``ALIAS``.
 
-An ``ALIAS`` to a non-``GLOBAL`` :ref:`Imported Target <Imported Targets>`
-has scope in the directory in which the alias is created and below.
-The :prop_tgt:`ALIAS_GLOBAL` target property can be used to check if the
-alias is global or not.
+.. versionadded:: 3.11
+  An ``ALIAS`` can target a ``GLOBAL`` :ref:`Imported Target <Imported Targets>`
+
+.. versionadded:: 3.18
+  An ``ALIAS`` can target a non-``GLOBAL`` Imported Target. Such alias is
+  scoped to the directory in which it is created and subdirectories.
+  The :prop_tgt:`ALIAS_GLOBAL` target property can be used to check if the
+  alias is global or not.
 
 ``ALIAS`` targets can be used as targets to read properties
 from, executables for custom commands and custom targets.  They can also be