Errors when building users guide

I see errors like this when using 'make html' in the topdir of the ghc repo: ---- /vol/hosts/cueball/workspace/github/ghc/docs/users_guide/flags.rst:15: SEVERE: Problems with "include" directive path: InputError: [Errno 2] No such file or directory: 'docs/users_guide/flags-verbosity.gen.rst'. ---- What am I doing wrong or not doing? -harendra