Fix building docs at crate/crate by removing stray README.md

[amotl]

Problem

@BaurzhanSakhariev just reported:

5.9.1 tag creation failed with

Warning, treated as error:
...crate/docs/_out/html/_static/vendor/furo/README.md:document isn't included in any toctree
Docs build failed. Aborting

Does it look familiar to anyone?

[amotl]

Evaluation

For some reason, this informative README.md made it into the documentation tree and was picked up by Sphinx. That is clearly not intended, and we don't know why it (suddenly!?) happens on the blackbox setup of crate/crate.

Solution

Let's try to fix that problem by just renaming this file to README.txt.

[amotl]

@BaurzhanSakhariev reported:

Cleaning up docs directory helped.

🤷