Help: Revise docs on Scripting Commands

Revise docs for all "Scripting Commands", except four find_XXX
that use a macro suite of their own.

* Take full advantage of the improved syntax highlighting.
* Make consequential use of <..> placeholders.
* Clarify things here and there in the text.

Specific improvements to some command docs:

* "math": Correct description of novel hexadecimal capability.
* "if", "foreach", "while": Provide link to "endif" etc
* "foreach", "while": Mention "break" and "continue".
* "foreach": Simplify explanation of ``RANGE`` and ``IN`` signatures;
   advise against negative arguments or reverse ranges (compare issue #18461)
* "endif", "endfunction" etc: Explain that the argument is optional and
   maintained for compatibility only

1 files changed, 10 insertions, 20 deletions

diff --git a/Help/command/get_filename_component.rst b/Help/command/get_filename_component.rst
index f11c0fc..3e3c9c3 100644
--- a/Help/command/get_filename_component.rst
+++ b/Help/command/get_filename_component.rst
@@ -3,13 +3,11 @@ get_filename_component
 
 Get a specific component of a full filename.
 
-------------------------------------------------------------------------------
+.. code-block:: cmake
 
-::
-
-  get_filename_component(<VAR> <FileName> <COMP> [CACHE])
+  get_filename_component(<var> <FileName> <mode> [CACHE])
 
-Set ``<VAR>`` to a component of ``<FileName>``, where ``<COMP>`` is one of:
+Sets ``<var>`` to a component of ``<FileName>``, where ``<mode>`` is one of:
 
 ::
 
@@ -24,15 +22,11 @@ The longest file extension is always considered.  If the optional
 ``CACHE`` argument is specified, the result variable is added to the
 cache.
 
-------------------------------------------------------------------------------
-
-::
+.. code-block:: cmake
 
-  get_filename_component(<VAR> <FileName>
-                         <COMP> [BASE_DIR <BASE_DIR>]
-                         [CACHE])
+  get_filename_component(<var> <FileName> <mode> [BASE_DIR <dir>] [CACHE])
 
-Set ``<VAR>`` to the absolute path of ``<FileName>``, where ``<COMP>`` is one
+Sets ``<var>`` to the absolute path of ``<FileName>``, where ``<mode>`` is one
 of:
 
 ::
@@ -41,7 +35,7 @@ of:
  REALPATH  = Full path to existing file with symlinks resolved
 
 If the provided ``<FileName>`` is a relative path, it is evaluated relative
-to the given base directory ``<BASE_DIR>``.  If no base directory is
+to the given base directory ``<dir>``.  If no base directory is
 provided, the default base directory will be
 :variable:`CMAKE_CURRENT_SOURCE_DIR`.
 
@@ -49,16 +43,12 @@ Paths are returned with forward slashes and have no trailing slashes.  If the
 optional ``CACHE`` argument is specified, the result variable is added to the
 cache.
 
-------------------------------------------------------------------------------
-
-::
+.. code-block:: cmake
 
-  get_filename_component(<VAR> <FileName>
-                         PROGRAM [PROGRAM_ARGS <ARG_VAR>]
-                         [CACHE])
+  get_filename_component(<var> <FileName> PROGRAM [PROGRAM_ARGS <arg_var>] [CACHE])
 
 The program in ``<FileName>`` will be found in the system search path or
 left as a full path.  If ``PROGRAM_ARGS`` is present with ``PROGRAM``, then
 any command-line arguments present in the ``<FileName>`` string are split
-from the program name and stored in ``<ARG_VAR>``.  This is used to
+from the program name and stored in ``<arg_var>``.  This is used to
 separate a program name from its arguments in a command line string.