Support for ~~`Fragment`~~ and named slots

[JulianCataldo]

Hey there!

Actually, passing the Fragment component like this doesn't seems to work:

  <Markdown
    content={content}
    components={{
      // ...,
      Fragment,
      Tabs,
    }}
  />

In a MD:

<Fragment slot="tab-1">Tab 1</Fragment>

Fragment is skipped Using a real elem. like div fixes this. However named slots are not supported. The default one are working well.

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EDIT: Ok, I've done some test, and passing Fragment is effective, it's the named slots which are the culprit.