just create the page and fill basic install notes

I think i was expecting us to have multiple such styles, but this is
just not happening, so it seems odd to just have that one extra
directory with only one file in it.

Having the file named "mdl" something will also make it easier to
understand what it's about.

I'm not sure why that's flagged as a typo at all. A "crate" is a
perfectly fine english word. I have looked around the dicts and
everywhere and couldn't figure it out. But now i need to stop shaving
yacks and move forward already.

The previous page was standalone, not linked from anywhere, so really
hard to find. It also seems to me small enough that it can fit in
another page. We don't have docs specifically for donate, so let's
cram this in the CRM docs.

Master

See merge request !41