Update requirements docs with a note about MySQL 8 issues that may affect some sites

I added the original issue text in the issue summary, as my subsequent reply doesn't really make sense unless you can see what I was replying to. Also, the OP was asking a fair question - changing major DB version can cause problems on any site in general, and it is wise to look for guidance before attempting it on a complex Drupal site.

Regardless, in the case of upgrading a Drupal site to MySQL 8, there are certain situations that we know about, notably with the Voting API module and the Group module, where updating the database can cause data destruction because of 🐛 Make Drupal\Core\Database\Schema work with reserved keywords for naming Fixed for example.

Since it doesn't seem that this problem will every be fixed in D9, documenting a way to avoid this critical problem is the least that could be done. But it needs to be done in a manner that ensures people will see it BEFORE attempting the upgrade. Because after failing the database upgrade is too late.

Hi Team,

Do we have any document for safely updating mysql 5.7 to mysql 8.0 for Drupal 9.5 website.

Regards