Add some notes about the contexts in which this fragment for translation will be used. N.B. Any comment before a translated string that starts with
will be included in the .po files (and visible under the 'Details' heading for the string in Transifex), so we should use these comments liberally to help translators understand the context in which text appears. In the longer term, we should move to using whole sentences rather than fragments - the effects of context will vary across languages, and what will work in English as an independent phrase will require sentence context in another language.