Decide wether to use FAQ or F.A.Q.

Some pages contain FAQ sections, however under different titles, compare e. g. https://doc.zih.tu-dresden.de/data_lifecycle/workspaces/#faq and https://doc.zih.tu-dresden.de/software/big_data_frameworks/#faq. Decide for one version or rephrase title altogether! To avoid this in the future:

• add description to https://doc.zih.tu-dresden.de/contrib/content_rules/
• add check to CI

It is "FAQ".

Since I never ever saw "F.A.Q." in the wild, I don't think we need to add a rule to the content rules. The same holds for the suggested CI check.

mentioned in merge request !480 (merged)

mentioned in commit d63acbb2

closed with merge request !480 (merged)