message: Add comment in section for adding new component to update config file.
diff: .. note :: This stuff is pulled from older content we had lying around.
  It needs to be updated, checked for correctness, gaps filled in, etc.
  +Note: when adding a new component, config.hpp.in file must be updated with
  +#cmakedefine AXOM_USE_<new-component-name>
  +
  ======================================================
  Adding a New Axom Component
  ======================================================
  