ctest_build: spruce up the documentation a bit

Adds markup and links to other sections.

Help/command/ctest_build.rst

@@ -8,27 +8,27 @@ Build the project.
   ctest_build([BUILD build_dir] [TARGET target] [RETURN_VALUE res]
               [APPEND][NUMBER_ERRORS val] [NUMBER_WARNINGS val])
 
-Builds the given build directory and stores results in Build.xml.  If
-no BUILD is given, the CTEST_BINARY_DIRECTORY variable is used.
+Builds the given build directory and stores results in Build.xml.  If no
+``BUILD`` is given, the :variable:`CTEST_BINARY_DIRECTORY` variable is used.
 
-The TARGET variable can be used to specify a build target.  If none is
+The ``TARGET`` variable can be used to specify a build target.  If none is
 specified, the "all" target will be built.
 
-The RETURN_VALUE option specifies a variable in which to store the
-return value of the native build tool.  The NUMBER_ERRORS and
-NUMBER_WARNINGS options specify variables in which to store the number
+The ``RETURN_VALUE`` option specifies a variable in which to store the
+return value of the native build tool.  The ``NUMBER_ERRORS`` and
+``NUMBER_WARNINGS`` options specify variables in which to store the number
 of build errors and warnings detected.
 
-The APPEND option marks results for append to those previously
-submitted to a dashboard server since the last ctest_start.  Append
+The ``APPEND`` option marks results for append to those previously
+submitted to a dashboard server since the last :command:`ctest_start`.  Append
 semantics are defined by the dashboard server in use.
 
-The QUIET option suppresses any CTest-specific non-error output
+The ``QUIET`` option suppresses any CTest-specific non-error output
 that would have been printed to the console otherwise.  The summary
 of warnings / errors, as well as the output from the native build tool
 is unaffected by this option.
 
-If set, the contents of the variable CTEST_BUILD_FLAGS are passed as
-additional arguments to the underlying build command. This can e.g. be
-used to trigger a parallel build using the -j option of make. See
+If set, the contents of the variable ``CTEST_BUILD_FLAGS`` are passed as
+additional arguments to the underlying build command. This can, e.g., be used
+to trigger a parallel build using the ``-j`` option of make. See
 :module:`ProcessorCount` for an example.