Update the public Generator references now that it's live

[johnnymatthews]

One user in Discord asked whether the public Generator mentioned in the docs was live yet. The team confirmed it is, and that several teams are already onboarded and running against it. The docs still say the opposite in three places:

• content/run/run-a-host/install/index.md says "A public Generator client you can point at is coming; this page will link it here once it's live. Until then, run your own." The claim appears twice, once in the prerequisites and once in the Docker section, where it also promises "a ready-to-run query" once the endpoint is linked.
• content/run/operations/troubleshooting/index.md says "A public Generator client you can point at is planned; this page will link it once it's live."

A Host operator reading this runs their own Generator or hunts for a peer, when there's a public one they can point at. #290 was the earlier issue for this and it's closed, but the coming/planned text is still in place.

• Get the public Generator's endpoint and peer ID from the team.
• Replace the coming/planned text on both pages and link the endpoint.
• Add the promised ready-to-run query on the install page, if that's still the plan.