Edit a glossary term's text, variants, part of speech, note, case
sensitivity or tags. Attributes left out keep their values. The term's ID
stays the same.

Anyone who can edit the glossary can edit its terms: organization
administrators, and roles on a project linked to the glossary whose
editing the glossary's permissions leave on. Editing terms needs a plan
that supports glossary editing.

A 409 means another term of the glossary already has one of the term's
new variants with its part of speech. A body whose id names another
term than the path gets a 409 too, as JSON:API requires.