minor symfony#20410 Add a note about updating phpdoc in a patch release (fabpot)

This PR was merged into the 5.4 branch.

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Add a note about updating phpdoc in a patch release

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d6d8bb8 Add a note about updating phpdoc in a patch release

Author: xabbuh

contributing/code/maintenance.rst

@@ -67,6 +67,9 @@ issue):
 * **Adding new deprecations**: After a version reaches stability, new
   deprecations cannot be added anymore.
 
+* **Adding or updating annotations**: Adding or updating annotations (PHPDoc
+  annotations for instance) is not allowed; fixing them might be accepted.
+
 Anything not explicitly listed above should be done on the next minor or major
 version instead. For instance, the following changes are never accepted in a
 patch version: