Use `<details>` on large listings?

[ShadowJonathan]

When working on https://github.com/matrix-org/mjolnir/issues/294 (in https://github.com/matrix-org/mjolnir/pull/376), and live-testing it in the management room, I got a comment that the listings simply were way too big, and that hiding the text would be useful.

There is an HTML tag called <details> that would allow this, the Element Web client already supporting rendering of this;

However, a quick look at the Element iOS client shows that it doesn't support it, and I don't know about Element Android.

This'd probably be nice in combination with the solution in #376, allowing users to hide massive walls of text but also quickly go to a specific subset of information in that large amount of text. (By just clicking the arrow next to the relevant header)