resolves #4 add job to runs linters in CI

.gitlab-ci.yml

@@ -0,0 +1,20 @@
+image: node:8
+stages:
+- setup
+- verify
+yarn:
+  stage: setup
+  script:
+  - npm install -g yarn
+  - yarn --cache-folder=.yarn-cache
+  cache:
+    paths:
+    - node_modules/
+    - .yarn-cache/
+lint:
+  stage: verify
+  cache:
+    policy: pull
+    paths:
+    - node_modules/
+  script: node_modules/.bin/gulp lint

README.adoc

@@ -1,6 +1,10 @@
 = Antora Default UI
 // Project URIs:
 :uri-project: https://gitlab.com/antora/antora-ui-default
+:uri-ci-pipelines: {uri-project}/pipelines
+:img-ci-status: {uri-project}/badges/master/pipeline.svg
+
+image:{img-ci-status}[CI Status (GitLab CI), link={uri-ci-pipelines}]
 
 This project is an archetype that demonstrates how to produce a UI bundle for use in an Antora-based documentation pipeline.