pub: add publishing workflow (#33)

* Remove old jenkins build
* Add new GH action for publishing
* Add license file
* Update readme

Author: planger

.github/workflows/publish.yml

@@ -0,0 +1,72 @@
+# Sample workflow for building and deploying a Hugo site to GitHub Pages
+name: Deploy Website
+
+on:
+  # Runs on pushes targeting the default branch
+  push:
+    branches: ["master"]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+# Allow one concurrent deployment
+concurrency:
+  group: "publish"
+  cancel-in-progress: true
+
+env:
+  WEBSITE_SOURCES_DIR: sources
+  WEBSITE_CONTENT_REPO: eclipse-emfcloud/emfcloud-website
+  WEBSITE_CONTENT_DIR: hugo-public-dist
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          submodules: recursive
+          fetch-depth: 0
+          token: ${{ secrets.GITHUB_TOKEN }}
+          path: ${{ env.WEBSITE_SOURCES_DIR }}
+      - name: Checkout content website
+        uses: actions/checkout@v3
+        with:
+          repository: ${{ env.WEBSITE_CONTENT_REPO }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+          path: ${{ env.WEBSITE_CONTENT_DIR }}
+
+      - name: Setup Hugo
+        uses: peaceiris/actions-hugo@v2
+        with:
+          hugo-version: '0.78.1'
+          extended: true
+
+      - name: Prune current content
+        working-directory: ${{ env.WEBSITE_CONTENT_DIR }}
+        run: git rm -rf *
+
+      - name: Build website
+        working-directory: ${{ env.WEBSITE_SOURCES_DIR }}
+        env:
+          # For maximum backward compatibility with Hugo modules
+          HUGO_ENVIRONMENT: production
+          HUGO_ENV: production
+        run: hugo --minify -d ${{ github.workspace }}/${{ env.WEBSITE_CONTENT_DIR }}
+
+      - name: Check for content changes
+        id: git-check
+        working-directory: ${{ env.WEBSITE_CONTENT_DIR }}
+        run: |
+          git add -A
+          echo ::set-output name=modified::$(if git diff --cached --exit-code --quiet; then echo "false"; else echo "true"; fi)
+      - name: Push content changes
+        if: steps.git-check.outputs.modified == 'true'
+        working-directory: ${{ env.WEBSITE_CONTENT_DIR }}
+        run: |
+          git config user.name ${{ github.event.head_commit.author.name }}
+          git config user.email ${{ github.event.head_commit.author.email }}
+          git config -l | grep 'http\..*\.extraheader' | cut -d= -f1 | xargs -L1 git config --unset-all
+          git remote set-url origin https://x-access-token:${{ secrets.GH_ACTION_TOKEN }}@github.com/${{ env.WEBSITE_CONTENT_REPO }}
+          git commit -am "${{ github.event.head_commit.message }}"
+          git push origin