Add github action for markdown linting

.github/workflows/markdown.yml

@@ -0,0 +1,26 @@
+# Copyright 2019 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: Markdown
+on:
+  pull_request:
+    branches:
+      - master
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: xt0rted/markdownlint-problem-matcher@v1
+      - run: (cd site && npm run lint-check)

Makefile

@@ -80,10 +80,7 @@ functions-examples-docker:
 	docker push gcr.io/kpt-dev/example-functions:v0.1.0
 
 lintdocs:
-	git clone git@github.com:igorshubovych/markdownlint-cli.git
-	(cd markdownlint-cli && npm i)
-	node markdownlint-cli/markdownlint.js --fix site/content || true
-	rm -rf markdownlint-cli
+	(cd site && npm run lint-fix)
 
 gencatalog:
 	rm site/content/en/guides/consumer/function/catalog/_index.md

site/markdownlint.json

@@ -0,0 +1,9 @@
+{
+  "default": true,
+  "MD001": false,
+  "MD013": false,
+  "MD024": false,
+  "MD025": false,
+  "MD040": false,
+  "MD046": false
+}