Document recommendations on how to use SELint while violating normal conventions

[dburgener]

6fbb752 Is adding a README section documenting some of the heuristics SELint uses to infer policy developer intent. A helpful augmentation of this would be to document recommendations for if a policy developer wants to violate those conventions while still using SELint (eg "disable such and such check", or "update the config in such and such a way")