Preview and Build website in docker container (#1668)

* start/build docs in docker

* restore old fashion

* fix release ci

.github/workflows/release.yml

@@ -127,7 +127,12 @@ jobs:
           asset_content_type: text/plain
       - uses: actions/setup-node@v1
         with:
-          node-version: '12.x'
+          node-version: "12.x"
+      - uses: actions/setup-python@v2
+        with:
+          python-version: "3.7"
+      - name: Clean md files
+        run: python ./hack/website/clean-md.py ./docs/en
       - name: Sync release to kubevela.io Repo
         env:
           SSH_DEPLOY_KEY: ${{ secrets.GH_PAGES_DEPLOY }}
@@ -136,4 +141,4 @@ jobs:
         run: |
           bash ./hack/website/release.sh
       - name: Update kubectl plugin version in krew-index
-        uses: rajatjindal/krew-release-bot@v0.0.38
+        uses: rajatjindal/krew-release-bot@v0.0.38