[IDEA] Inline document for filter operator and action widget about tiddlywiki5

[linonetwo]

See also #8230 @Jermolene

[Jermolene]

Hi @linonetwo I agree that it would be very useful to have programmatically integrated documentation for the core primitives.

What I would like to do is to repackage the reference documentation as a plugin so that people can have it available in their own wikis. We would use strict naming conventions so that it would be possible for tooling to extract structured documentation for a particular widget or filter operator. We would need to devise a scheme to allow for translated documentation plugins, and to allow the documentation to be extended by plugins.