Generate xmldoc descriptions for enum values

For example, `SHChangeNotify` adds `SHCNE_ID` and `SHCNF_FLAGS` enums, but neither the enum itself or the values have any xmldocs.

I don't know if the metadata for these exists, but it's documented at least: https://learn.microsoft.com/en-us/windows/win32/api/shlobj_core/nf-shlobj_core-shchangenotify

Start with the SHChangeNotify metadata and the SHCNE_ID and SHCNF_FLAGS enum definitions, then compare the available metadata with the linked Microsoft documentation. Done means the generated XML documentation includes descriptions for each enum and its values, with the generator's relevant validation or output checks passing.

Written by the indexing model from the issue text.