set FAQ version

We add a FAQ version of "28.0 2024-07-14" to `faq.md`
using a similar form of version strings as `next/rules.md`
and `next/guidelines.md`.

Ran `make faq` to perform and test the above under macOS.

faq.md

@@ -1,5 +1,7 @@
 # FAQ Table of Contents
 
+This is FAQ version **28.0 2024-07-14**.
+
 
 ## Section  0 - [Submitting entries to a new IOCCC](#faq0)
 - <a class="normal" href="#faq0_0">0.0  - How may I enter the IOCCC?</a>