Update docs workflow

.github/workflows/docs.yml

@@ -0,0 +1,50 @@
+name: Crystal Docs Generation
+
+on:
+  push:
+    branches: [ "docs" ]
+  pull_request:
+    branches: [ "docs" ]
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+# Allow only one concurrent deployment, skipping runs queued between the run in-progress and latest queued.
+# However, do NOT cancel in-progress runs as we want to allow these production deployments to complete.
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    container:
+      image: crystallang/crystal
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Generate docs
+      run: crystal docs
+    - name: Move docs to _site
+      run: mv docs/ _site/
+    - name: Upload artifact
+      uses: actions/upload-pages-artifact@v3
+
+# Deployment job
+deploy:
+  environment:
+    name: github-pages
+    url: ${{ steps.deployment.outputs.page_url }}
+  runs-on: ubuntu-latest
+  needs: build
+  steps:
+    - name: Deploy to GitHub Pages
+      id: deployment
+      uses: actions/deploy-pages@v4