Remove extra parentheses in docs

[arogachev]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌

[what-the-diff[bot]]

PR Summary

• Expansion of the sourcePaths array There were two new paths added to the 'sourcePaths' array under the 'yiisoft/db-migration' section. This will broaden the search range of your database migration files, especially those related to role-based access control (RBAC). This helps to seamlessly integrate additional features or updates into your application, without having to manually update the database schema each time.

[arogachev]

Thanks to @vjik for discovering it.