Flip direction of the 6.3 merge workflow

.github/workflows/automerge.yml

@@ -1,7 +1,7 @@
-name: Create PR to merge release into main branch
+name: Create PR to merge main into release branch
 # In the first period after branching the release branch,
 # we typically want to include many changes from `main` in the release branch.
-# This workflow automatically creates a PR to merge the release branch into the main.
+# This workflow automatically creates a PR to merge the main branch into the release branch.
 # Later in the release cycle we should stop this practice to avoid landing risky changes by disabling this workflow.
 # To do so, disable the workflow as described in https://docs.github.com/en/actions/managing-workflow-runs-and-deployments/managing-workflow-runs/disabling-and-enabling-a-workflow
 permissions:
@@ -12,11 +12,11 @@ on:
   workflow_dispatch:
 jobs:
   create_merge_pr:
-    name: Create PR to merge release into main branch
+    name: Create PR to merge main into release branch
     uses: swiftlang/github-workflows/.github/workflows/create_automerge_pr.yml@main
     with:
-      head_branch: release/6.3
-      base_branch: main
+      head_branch: main
+      base_branch: release/6.3
     permissions:
       contents: write
       pull-requests: write