Support for custom meta-tags #214

Hi!

This is more of a question than a feature request, because I really don't know if you'd be interested in this, and whether it's worth writing a proposal before discussing it a bit.

Is there any way right now to insert custom meta tags? For example, something like:

<meta name="fediverse:creator" content="@<user>@<instance>">

I reviewed prose's documentation but I couldn't find anything about it.

Thanks in advance!

Regards