Documentation generator doesn't handle settings property in assertion file

[pnevyk]

Some rules use settings property in their assertions definition, e.g. to show that the rule is not applied when onlyFilesWithFlowAnnotation setting option is set to true and there is no such annotation in the code. However, documentation generator doesn't handle this property at all, so in docs there is wrong use case of the rule which is considered not a problem, without any note about onlyFilesWithFlowAnnotation setting.

[gajus]

Easy PR.

[gajus]

Thank you @pnevyk

[pnevyk]

@gajus I am glad I could help :)