Markdown: Add support for <details>

[machour]

It would be nice to add support for <details> tag in GithubHtmlView:

Title

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Sub header 1

Hello there.

[ArvinH]

Hi, I want to take care of this one!
First time for RN but I'm trying 😄

[machour]

@ArvinH awesome, thank you!! 🎉
You may find our <ToggleView /> component handy: https://github.com/gitpoint/git-point/blob/master/src/components/toggle-view.component.js
Could you also try to use the same arrow as github? ► ▼

[housseindjirdeh]

@ArvinH thank you <3

Any questions about anything - don't hesitate to ask 🙌