minor #17991 [Bundles] new directory structure for doctrine resources (MrYamous)

This PR was squashed before being merged into the 5.4 branch.

Discussion
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[Bundles] new directory structure for doctrine resources

Fixes #16110

Commits
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9009092 [Bundles] new directory structure for doctrine resources

Author: OskarStark

bundles/best_practices.rst

@@ -167,10 +167,16 @@ Doctrine Entities/Documents
 
 If the bundle includes Doctrine ORM entities and/or ODM documents, it's
 recommended to define their mapping using XML files stored in
-``Resources/config/doctrine/``. This allows to override that mapping using the
+``config/doctrine/``. This allows to override that mapping using the
 :doc:`standard Symfony mechanism to override bundle parts </bundles/override>`.
 This is not possible when using annotations/attributes to define the mapping.
 
+.. caution::
+
+    The recommended bundle structure was changed in Symfony 5, read the
+    `Symfony 4.4 bundle documentation`_ for information about the old
+    structure.
+
 Tests
 -----
 
@@ -560,3 +566,4 @@ Learn more
 .. _`valid license identifier`: https://spdx.org/licenses/
 .. _`GitHub Actions`: https://docs.github.com/en/free-pro-team@latest/actions
 .. _`Travis CI`: https://docs.travis-ci.com/
+.. _`Symfony 4.4 bundle documentation`: https://symfony.com/doc/4.4/bundles.html#bundle-directory-structure