Define translation workflow / policy

[nlhkabu]

We need to answer the following questions:

1. What happens with translations when we update the (English) source?
2. When do we consider a language to be 'supported' and link to it from the PyPI footer?
3. What happens if a language is no longer maintained?

My 2c:

Updating English source

First, we need to reach out to the community to register maintainers for each language. When we update the UI copy:

1. The change is merged as normal
2. The UI falls back to the original English
3. We notify translators via Weblate that a new translation is required

Note: In some cases (e.g. fixing typos, formatting) translators may be able to use the translation memory to reduce the maintenance burden

When do we consider a language 'supported'?

If 90% (???) of strings are translated, we should link to it from the PyPI footer.

What happens if a language is no longer maintained?

We remove it from the PyPI footer if it falls below 90% (???) coverage