GF profile: DESC check to ban the word "free" from GF family descriptions

[davelab6]

Observed behaviour

The word "free" appears in DESC files but this may be misleading so we should use other words.

Related PRs are google/fonts#4443 and google/fonts#4444

We need a FB check to ensure the word (or its stems, freely, etc) doesn't re-enter, that will be run as part of the github.com/google/fonts repo CI.

Expected behaviour

FAIL any family with *free* in the DESC, unless its part of an allow-list with items like "free press" and so on.

Resources and exact process needed to replicate

I'll follow up on this issue with that list.