docs: adding action to notify discord

.github/workflows/notify-discord.yml

@@ -0,0 +1,14 @@
+name: Notify Discord on Release
+
+on:
+  release:
+    types: [published]   # fires only when a release is published
+
+jobs:
+  notify:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Send nicely-formatted embed to Discord
+        uses: SethCohen/github-releases-to-discord@v1
+        with:
+          webhook-url: ${{ secrets.DISCORD_WEBHOOK }}