Add notice or warning to Glossaries to avoid multi-translation entries

[garretthyder]

This stems from #188 and our discussions as a way to expose to Glossary editors that their entries should be 1-to-1 and if terms have multiple translations that each translation should be entered as a unique entry.

Am thinking a persistent notice on the top of Glossaries to indicate each translation should have it's own entry, and possibly a warning flagged when the entry translation contains a slash or comma separator.

Currently we have no notices on Glossary so we'll have to update the manifest to support Glossary pages.

[audrasjb]

Yep, this issue is really annoying :)

[garretthyder]

This is on hold until GlotPress 3.0 is released with support for multi-translation entries as handled here - GlotPress/GlotPress#947

Pushing a fix for this now would cause confusion as they wouldn't be able to resolve the flagged warning.