The two sniffs MediaWiki.Commenting.FunctionComment.MissingDocumentationPrivate and MediaWiki.Commenting.PropertyDocumentation.MissingDocumentationPrivate are already disabled for GrowthExperiments (or to be more precise: were never enabled, see the blame for
https://github.com/wikimedia/mediawiki-extensions-GrowthExperiments/blob/master/.phpcs.xml).

Should we also disable them for CommunityConfiguration?

• It might be nice to have a somewhat consistent code style across the team's code bases
• requiring a php-doc on private methods incentivizes doc-blocks that just repeat the method signature without adding addition information
• we can now add type-hints to properties, so requiring php-doc on the private ones should no longer be necessary