Higurashi mod descriptions need updating

The higurashi mod descriptions are out of date as compared to the wiki.

Also, since the BGM options are now "default", there is no longer any information about the BGM fix in the installer, nor any links to the april upate FAQ, so I think we should link to that FAQ in a dot point where we also mention the mod adds BGM fixes

Look for the mod description files in the repository, likely in a directory like 'mods' or 'descriptions'. Compare the current descriptions with the wiki to identify outdated information. Update the descriptions to reflect the current BGM options (now 'default') and add a link to the April update FAQ where BGM fixes are mentioned.

Written by the indexing model from the issue text.