Spindle can be added / verified as a Knot, eventually fails on repo creation. #415

For posterity:

While running through the hacking.md doc, I mistakenly tried to register my spindle instance, on port 6555, as a knot. The knot page allowed it to be verified, but when I went to create a repo it complained about xrpc incompatibility, because it's not a knot.

Akshay mentioned that it's probably because the xrpc can talk to the spindle and get xrpc/sh.tangled.owner as part of the verification flow, but there's no further verification that the service is actually a knot.

While going through hacking-on-tangled doc, I setup my local environment, ran the VM for a knot, verified that it was added and when I go to create a new repo I get "xrpc not supported on this knot" as an error in the repo/new page.