Support collapsible content

[IzaacJ]

Subject of the issue

I've used this to include my changelog in the app, but the collapsable sections aren't working as expected.

Steps to reproduce

Include the library, load a CHANGELOG.md that contains collapsible sections which has markdown in them, according to this gist.

<details>
<summary>This shouldn't be parsed</summary>

### Some other text that should be bigger.
</details>

Expected behaviour

The markdown inside the collapsible section should be parsed and rendered as well.

An Example

This shouldn't be parsed

Some other text that should be bigger.

Actual behaviour

The markdown inside the collapsible section is rendered raw. Content outside it is rendered as expected.

Screenshots

[doomed-neko]

i have 2 thins 2 say:
1- how did you made a collapasing thing?
2- you ca make it normal without the collapase thingy