Update URL for rpc.flashbots.net redirect

[bertmiller]

📝 Summary

We changed the docs. We need to update the URL that going to rpc.flashbots.net redirects to. I changed the URL in a few places.

⛱ Motivation and Context

We changed the docs. We need to update the URL that going to rpc.flashbots.net redirects to.

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✅ I have run these commands

• [ ] make lint
• [ ] make test
• [ ] go mod tidy

[bertmiller]

Hold off on this.