Help: Format execute_process command documentation

Use a code-block for the signature.  Format the options as a definition
list.

Help/command/execute_process.rst

@@ -3,7 +3,7 @@ execute_process
 
 Execute one or more child processes.
 
-::
+.. code-block:: cmake
 
   execute_process(COMMAND <cmd1> [args1...]]
                   [COMMAND <cmd2> [args2...] [...]]
@@ -21,28 +21,41 @@ Execute one or more child processes.
                   [ERROR_STRIP_TRAILING_WHITESPACE])
 
 Runs the given sequence of one or more commands with the standard
-output of each process piped to the standard input of the next.  A
-single standard error pipe is used for all processes.  If
-WORKING_DIRECTORY is given the named directory will be set as the
-current working directory of the child processes.  If TIMEOUT is given
-the child processes will be terminated if they do not finish in the
-specified number of seconds (fractions are allowed).  If
-RESULT_VARIABLE is given the variable will be set to contain the
-result of running the processes.  This will be an integer return code
-from the last child or a string describing an error condition.  If
-OUTPUT_VARIABLE or ERROR_VARIABLE are given the variable named will be
-set with the contents of the standard output and standard error pipes
-respectively.  If the same variable is named for both pipes their
-output will be merged in the order produced.  If INPUT_FILE,
-OUTPUT_FILE, or ERROR_FILE is given the file named will be attached to
-the standard input of the first process, standard output of the last
-process, or standard error of all processes respectively.  If
-OUTPUT_QUIET or ERROR_QUIET is given then the standard output or
-standard error results will be quietly ignored.  If more than one
-OUTPUT_* or ERROR_* option is given for the same pipe the precedence
-is not specified.  If no OUTPUT_* or ERROR_* options are given the
-output will be shared with the corresponding pipes of the CMake
-process itself.
-
-The execute_process command is a newer more powerful version of
-exec_program, but the old command has been kept for compatibility.
+output of each process piped to the standard input of the next.
+A single standard error pipe is used for all processes.
+
+Options:
+
+WORKING_DIRECTORY
+ The named directory will be set as the current working directory of
+ the child processes.
+
+TIMEOUT
+ The child processes will be terminated if they do not finish in the
+ specified number of seconds (fractions are allowed).
+
+RESULT_VARIABLE
+ The variable will be set to contain the result of running the processes.
+ This will be an integer return code from the last child or a string
+ describing an error condition.
+
+OUTPUT_VARIABLE, ERROR_VARIABLE
+ The variable named will be set with the contents of the standard output
+ and standard error pipes, respectively.  If the same variable is named
+ for both pipes their output will be merged in the order produced.
+
+INPUT_FILE, OUTPUT_FILE, ERROR_FILE
+ The file named will be attached to the standard input of the first
+ process, standard output of the last process, or standard error of
+ all processes, respectively.
+
+OUTPUT_QUIET, ERROR_QUIET
+ The standard output or standard error results will be quietly ignored.
+
+If more than one ``OUTPUT_*`` or ``ERROR_*`` option is given for the
+same pipe the precedence is not specified.
+If no ``OUTPUT_*`` or ``ERROR_*`` options are given the output will
+be shared with the corresponding pipes of the CMake process itself.
+
+The :command:`execute_process` command is a newer more powerful version of
+:command:`exec_program`, but the old command has been kept for compatibility.