Remove obsolete section about handling merge-up pull requests

Author: alcaeus

RELEASING.md

@@ -82,14 +82,6 @@ in the MongoDB documentation must be updated to account for new releases. Make
 sure to update both MongoDB and Language compatibility tables, as shown in
 [this pull request](https://github.com/mongodb/docs-ecosystem/pull/642).
 
-## Handle merge-up pull request
-
-After the release automation pushes changes to the stable branch the release was
-created from, the merge automation will create a new pull request to merge these
-changes into the next versioned branch. Since version changes always create a
-conflict, follow the "Ignoring Changes" section in the pull request to resolve
-the conflicts and merge the pull request once the build completes.
-
 ## Announce release
 
 Significant release announcements should also be posted in the