Add docs workflow

Author: dsyer

.github/workflows/docs.yml

@@ -0,0 +1,46 @@
+name: Deploy Docs
+run-name: ${{ format('{0} ({1})', github.workflow, github.event.inputs.build-refname || 'all') }}
+on:
+  workflow_dispatch:
+    inputs:
+      build-refname:
+        description: Enter git refname to build (e.g., main).
+        required: false
+  push:
+    branches: [ docs-build ]
+permissions:
+  contents: write
+jobs:
+  build:
+    if: github.repository_owner == 'spring-projects-experimental'
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 5
+    - name: Set up JDK 17
+      uses: actions/setup-java@v4
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+        cache: maven
+    - name: Set up refname build
+      if: github.event.inputs.build-refname
+      run: |
+        git fetch --depth 1 https://github.com/$GITHUB_REPOSITORY ${{ github.event.inputs.build-refname }}
+        export BUILD_REFNAME=${{ github.event.inputs.build-refname }}
+        echo "BUILD_REFNAME=$BUILD_REFNAME" >> $GITHUB_ENV
+        export BUILD_VERSION=$(git cat-file --textconv FETCH_HEAD:pom.xml | python3 -c "import xml.etree.ElementTree as xml; from sys import stdin; print(xml.parse(stdin).getroot().find('{http://maven.apache.org/POM/4.0.0}version').text)")
+        echo BUILD_VERSION=$BUILD_VERSION >> $GITHUB_ENV
+    - name: Run Antora
+      run: |
+        ./mvnw -pl spring-grpc-docs antora
+    - name: Publish Docs
+      uses: spring-io/spring-doc-actions/[email protected]
+      with:
+        docs-username: ${{ secrets.DOCS_USERNAME }}
+        docs-host: ${{ secrets.DOCS_HOST }}
+        docs-ssh-key: ${{ secrets.DOCS_SSH_KEY }}
+        docs-ssh-host-key: ${{ secrets.DOCS_SSH_HOST_KEY }}
+        site-path: spring-grpc-docs/target/antora/site