Add docs build workflow

Author: zajrik

.github/workflows/build_indev_docs.yml

@@ -0,0 +1,50 @@
+name: Build Indev Docs
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    name: Build indev docs
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v1
+
+      - name: Install Node v12
+        uses: actions/setup-node@v1
+        with:
+          node-version: 12
+
+      - name: Install dependencies
+        run: |
+          npm install
+
+      - name: Clone gh-pages branch
+        run: git clone https://${{ github.actor }}:${{ secrets.DOCS_TOKEN }}@github.com/${{ github.repository }}.git -b gh-pages ../yamdbf-docs
+
+      - name: Build docs
+        run: |
+          npm run build
+          npm run docs:indev
+
+      - name: Build localization string list
+        run: npm run localization
+
+      - name: Check if commit is needed
+        id: git_status
+        run: |
+          cd ../yamdbf-docs
+          echo "##[set-output name=status;]$(git status | grep 'nothing to commit')"
+
+      - name: Make commit and push
+        if: contains(steps.git_status.outputs.status, 'nothing to commit') != true
+        run: |
+          cd ../yamdbf-docs
+          git config --global user.name "${{ github.actor }}"
+          git config --global user.email "${{ github.actor}}@users.noreply.github.com"
+          git add --all
+          git commit -m "Build docs from master: ${{ github.sha }}"
+          git push origin gh-pages