docs: add workflow to assign PR to its author

Author: Anmol-Baranwal

.github/workflows/author-assign-pr.yml

@@ -0,0 +1,16 @@
+name: "Author Assign PR"
+
+on:
+  pull_request_target:
+    types: [opened, reopened]
+
+permissions:
+  pull-requests: write
+
+jobs:
+  assign-author:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: toshimaru/auto-author-assign@v1.6.2
+        with:
+          repo-token: "${{ secrets.GITHUB_TOKEN }}" # GITHUB_TOKEN will be used by default