Make "Compose tips" (long version of tips) for text formats discoverable from "Formatting options" fieldset

This issue arises from this issue, summarized here.

In brief: for the Token Filter module, the short-form tips for the text filter, which appears in the "Formatting options" fieldset, doesn't show what tokens can be used. The long-form tips, which appears on the "Compose tips" page for the format (at path /filter/tips/<format>), includes the relevant token browser. This situation led to the realization that in general, there's no easy way to go to the "Compose tips" page for a text format or otherwise see the long-form tips from the "Formatting options" fieldset, or for a user to even know that more tips information is available.

A simple fix might be to simply add to the bottom of the short-form tips a link to the long-form "Compose tips" page, called something like "more information".

A perhaps nicer fix might be to allow the user to toggle between the short-form and long-form display within "Formatting options", or to toggle the long-form display of tips as an overlay—in either case, avoiding having to leave the page to see the detailed description.

Is this notion worth pursuing? If so, I would be willing to work on a PR.