Use github action to check and verify doc

.github/workflows/check_doc.yml

@@ -0,0 +1,20 @@
+name: Check Documentation
+
+on:
+  pull_request:
+
+jobs:
+
+  docs:
+    name: Check, verify and build documentation
+    runs-on: ubuntu-latest
+
+    steps:
+
+      - name: Check out code
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Check documentation
+        run: make docs-pull-images docs

.travis.yml

@@ -16,7 +16,6 @@ env:
 
 script:
 - echo "Skipping tests... (Tests are executed on SemaphoreCI)"
-- if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then travis_retry make docs-pull-images && make docs; fi
 
 before_deploy:
   - >

docs/check.Dockerfile

@@ -24,8 +24,8 @@ RUN apk --no-cache --no-progress add \
 RUN npm config set unsafe-perm true
 
 RUN npm install --global \
-    markdownlint@0.17.2 \
-    markdownlint-cli@0.19.0
+    markdownlint@0.22.0 \
+    markdownlint-cli@0.26.0
 
 # Finally the shell tools we need for later
 # tini helps to terminate properly all the parallelized tasks when sending CTRL-C