#207 check markdown links

Also move dockerfile-lint and shellcheck out of the integration test.

Signed-off-by: Jeremias Weber <jeremias.weber@cloudogu.com>

Jenkinsfile

@@ -29,6 +29,19 @@ parallel(
           git.clean("")
         }
 
+        stage('Check Markdown Links') {
+            Markdown markdown = new Markdown(this)
+            markdown.check()
+        }
+
+        stage('Lint') {
+          lintDockerfile()
+        }
+
+        stage('Shellcheck') {
+          shellCheck("resources/startup.sh")
+        }
+
         stage('Build') {
           setupMaven(mvn)
           // Tui-Editor 1.4.10 has git:// dependencies.
@@ -105,14 +118,6 @@ parallel(
             git.clean("")
           }
 
-          stage('Lint') {
-            lintDockerfile()
-          }
-
-          stage('Shellcheck') {
-            shellCheck("resources/startup.sh")
-          }
-
           try {
             stage('Provision') {
               ecoSystem.provision("/dogu")