Set doc deployment on release publication

The docs should be deployed when a new release is publishing. There is
no point to deploy the docs every time when the master branch is
updated. The proposed change sets automatic doc deployment only on a
new release publication or manually.

Author: vitcpp

.github/workflows/deploy-docs.yml

@@ -1,10 +1,10 @@
 name: Build and Deploy Docs
 
-# Deploy docs only for master
+# Deploy docs when a new release is published or manually
 on:
-  push:
-    branches:
-      - "master"
+  release:
+    types: [published]
+  workflow_dispatch:
 
 # Allow deployment to GitHub Pages
 permissions: