[docs] Add regex to remove generated repository docsblock

[TomasVotruba]

A new regex should be added to https://github.com/symplify/coding-standard/blob/main/src/Fixer/Commenting/RemoveUselessDefaultCommentFixer.php, to handle this case:

- * This class was generated by the Doctrine ORM. Add your own custom
- * repository methods below.

Todo

• add regex
• add test fixture as well

[samsonasik]

#61