Suggestion: exclude @internal

[rbuckton]

TypeScript supports --stripInternal as an advanced compiler flag, in which declarations that have an @internal tag in their comments are stripped from output declaration files. Ideally, TypeDoc should exclude declarations from documentation marked with /** @internal */, similar to the logic here: https://github.com/rbuckton/iterable-query/blob/refactor/src/typedoc-plugin-custom/plugin.ts#L381.

This may need to be configurable, as the typedoc-plugin-internal-external package also uses @internal by default.

[aciccarello]

Thanks for your feedback @rbuckton. There already is some discussion of this in #364

You bring up a good point about the effect ignoring it would have on plugin users. Maybe @christopherthielen could provide some feedback. His while plugin allows using another tag name I imagine many use the default of @internal.