Add missing pages to documentation (#1172)

* Create spinnakerTriggerPipeline.md
* Update mkdocs.yml

documentation/docs/steps/spinnakerTriggerPipeline.md

@@ -0,0 +1,9 @@
+# ${docGenStepName}
+
+## ${docGenDescription}
+
+## ${docGenParameters}
+
+## ${docGenConfiguration}
+
+## ${docJenkinsPluginDependencies}