Document \debug pages

[jseldess]

Based on cockroachdb/cockroach#20690, we'll expose 4 /debug pages to users in 2.0. We should add docs on how to understand and use these pages:

• Node Diagnostics page: "I want to know how my nodes are configured"
• Problem Ranges report: "I want to know which ranges are causing problems"
• Network Diagnostics page: "I want to know if my nodes can talk to each other on the network"
• Certificates page: "I want to check if my certificates are configured properly"

[jseldess]

@Amruta-Ranade, can you please set up a meeting with @dianasaur323 and myself to discuss what's needed here?

@dianasaur323, is this represented on the 2.0 roadmap? If so, can you send me that link. Also, can you help identify the devs who are experts on each of the 4 debug pages? We probably want to have them in the meeting.

[dianasaur323]

Do we still want a meeting here? I'm heading out on Friday! That being said, you can always book me while I'm out during one of my 9-12 open slots marked on my calendar

[Amruta-Ranade]

@dianasaur323 @jseldess Yes! Sorry, I thought I already set up the meeting, but that was just in my head. Doing it now.

[Amruta-Ranade]

As discussed with Josue, not a priority for 2.0

[dianasaur323]

cc @piyush-singh since we just talked about this

[jseldess]

Replaced by #2373.