docs: add note

Author: kenjis

contributing/pull_request.md

@@ -204,6 +204,9 @@ working on your contribution.
   next bug fix version will be developed.
 - PRs with any enhancement should be sent to next minor version branch, e.g. __"4.6"__
 
+> [!NOTE]
+> If you sent your PR to the wrong branch, see
+> [Contribution Workflow](./workflow.md#if-you-sent-to-the-wrong-branch).
 
 The __"master"__ branch will always contain the latest stable version and is kept
 clean so a "hotfix" (e.g. an emergency security patch) can be applied to the