Update metrics documentation

[robbieheywood]

What happened:

agones_grpc_io_server_server_latency_bucket isn't documented in the metrics page at https://agones.dev/site/docs/guides/metrics/.

What you expected to happen:

https://agones.dev/site/docs/guides/metrics/ is updated to include all current metrics

How to reproduce it (as minimally and precisely as possible):

Go to https://agones.dev/site/docs/guides/metrics/

Anything else we need to know?:

n/a

Environment:

• Agones version:
• Kubernetes version (use kubectl version):
• Cloud provider or hardware configuration:
• Install method (yaml/helm):
• Troubleshooting guide log(s):
• Others:

[markmandel]

@robbieheywood if you can work out what this metric is for, we would love a pull request! 😃

[gongmax]

It's not a documentation issue since Agones doesn't expose such a metric named agones_grpc_io_server_server_latency_bucket. Or do you mean grpc.io/server/server_latency?

Closing this for now. Please reopen if you think Agones is missing some metrics that should be exposed. Thanks.