[Done] Proposed Repositories Organization

@Pertti I like "codeigniter4" as an organization name, for identity and branding.
CodeIgniter5 would be some years down the road (5+).
FWIW, a quick search on github revealed over two dozen "organization names" with the word "codeigniter" embedded, not ust "codeigniter" or "codeigniter3".

I guess the thinking is if it gets to 5, it'll be completely new thing and not compatible?

That's fair. Just need to pre-register couple of versions before someone else gets their hands on it

I assume there's not going to be that many "side projects" to CI4, compared to how lets say Laravel does it, with tons of extension projects available.

Either way, looking quite forward to 4