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, 8 insertions, 6 deletions

diff --git a/Help/command/variable_watch.rst b/Help/command/variable_watch.rst
index a2df058..ce69bcf 100644
--- a/Help/command/variable_watch.rst
+++ b/Help/command/variable_watch.rst
@@ -3,11 +3,13 @@ variable_watch
 
 Watch the CMake variable for change.
 
-::
+.. code-block:: cmake
 
-  variable_watch(<variable name> [<command to execute>])
+  variable_watch(<variable> [<command>])
 
-If the specified variable changes, the message will be printed about
-the variable being changed.  If the command is specified, the command
-will be executed.  The command will receive the following arguments:
-COMMAND(<variable> <access> <value> <current list file> <stack>)
+If the specified ``<variable>`` changes, a message will be printed
+to inform about the change.
+
+Additionally, if ``<command>`` is given, this command will be executed.
+The command will receive the following arguments:
+``COMMAND(<variable> <access> <value> <current_list_file> <stack>)``