Using IPFS Discord as default chat channel

[bmann]

I’ve arranged to create a #wnfs channel in the IPFS Discord chat as the companion to this discussion forum.

We should mention it in the README and elsewhere.

cc @b5 @expede

and @RangerMauve who prompted this ;)

[matheus23]

We decided in #30 that that'd be a better fit for the organization as a whole:
https://github.com/wnfs-wg