Document guidelines to help plugin writers so that they plan and document an uninstall feature
From a conversation with Dominic Cleal :
"Some plugins should have an uninstallation/purge procedure which removes certain data from Foreman's database. As plugins get more advanced, it's likely that they leave things like STI data in tables or foreign keys that might interfere with running of the standalone Foreman app."
Document this with plugin documentation. May be uniformising the way plugins uninstall themselves.