Add a comment listing a few required plugins in the Jenkinsfile

Jenkinsfile

@@ -11,6 +11,12 @@ def buildTarget(String path, String rpmArch = 'noarch', String debArch = 'noarch
 
 String windowsSuffix = '-windows'
 
+/* Required Plugins:
+    - CMake
+    - Sidebar Link
+    - Workspace Cleanup
+*/
+
 pipeline { // Multi-branch pipeline script for Yerbacon.
     agent any