Convert builtin help to reStructuredText source files

Run the convert-help.bash script to convert documentation:

 ./convert-help.bash "/path/to/CMake-build/bin"

Then remove it.

Help/command/include_external_msproject.rst

@@ -0,0 +1,23 @@
+include_external_msproject
+--------------------------
+
+Include an external Microsoft project file in a workspace.
+
+::
+
+  include_external_msproject(projectname location
+                             [TYPE projectTypeGUID]
+                             [GUID projectGUID]
+                             [PLATFORM platformName]
+                             dep1 dep2 ...)
+
+Includes an external Microsoft project in the generated workspace
+file.  Currently does nothing on UNIX.  This will create a target
+named [projectname].  This can be used in the add_dependencies command
+to make things depend on the external project.
+
+TYPE, GUID and PLATFORM are optional parameters that allow one to
+specify the type of project, id (GUID) of the project and the name of
+the target platform.  This is useful for projects requiring values
+other than the default (e.g.  WIX projects).  These options are not
+supported by the Visual Studio 6 generator.