Automate this check

[plaindocs]

Inspired by #1961 I added the check to vale:

❯ vale docs

 docs/conf/australia/2022/news/thank-you-recap.rst
 19:85  error  Use 'Write the Docs' instead    WTD.Branding 
               of 'Write The Docs'                          

 docs/slack.rst
 213:8  error  Don't say 'black sheep'  WTD.inclusivity-avoid 

✖ 2 errors, 0 warnings and 0 suggestions in 1348 files.

I'm not sure why the first one hasn't triggered our CI though?

---

:books: Documentation preview :books:: https://writethedocs-www--1962.org.readthedocs.build/

[plaindocs]

OK, it is detecting it, but returning success regardless

So something is misconfigured.

(Black sheep has already been removed on main)

[plaindocs]

Success