Add top level metrics document to summarize monitoring endpoints (#5923)

Minio server supports healthcheck and prometheus related
unauthenticated endpoints. This document summarizes this
information in a single place and add links for more detailed
documentation if needed.

docs/metrics/README.md

@@ -0,0 +1,20 @@
+## Minio Monitoring Guide
+
+Minio server exposes monitoring data over un-authenticated endpoints so monitoring tools can pick the data without you having to share Minio server credentials. This document lists the monitoring endpoints and relevant documentation.
+
+### Healthcheck Probe
+
+Minio server has two healthcheck related endpoints, a liveness probe to indicate if server is working fine and a readiness probe to indicate if server is not accepting connections due to heavy load.
+
+- Liveness probe available at `/minio/health/live`
+- Readiness probe available at `/minio/health/ready`
+
+Read more on how to use these endpoints in [Minio healthcheck guide](./healthcheck/README.md).
+
+### Prometheus Probe
+
+Minio server exposes Prometheus compatible data on a single endpoint.
+
+- Prometheus data available at `/minio/prometheus/metrics`
+
+To use this endpoint, setup Prometheus to scrape data from this endpoint. Read more on how to use Prometheues to monitor Minio server in [How to monitor Minio server with Prometheus](https://github.com/minio/cookbook/blob/master/docs/how-to-monitor-minio-with-prometheus.md).

docs/healthcheck/README.md → docs/metrics/healthcheck/README.md

@@ -4,11 +4,11 @@ Minio server exposes two un-authenticated, healthcheck endpoints - liveness prob
 
 ### Liveness probe
 
-This probe is used to identify situations where the server is running but may not behave optimally, i.e. sluggish response or corrupt backend. Such problems can be *only* fixed by a restart.
+This probe is used to identify situations where the server is running but may not behave optimally, i.e. sluggish response or corrupt back-end. Such problems can be *only* fixed by a restart.
 
 Internally, Minio liveness probe handler does a ListBuckets call. If successful, the server returns 200 OK, otherwise 503 Service Unavailable.
 
-When liveness probe fails, Kubernetes like platforms restart the container. 
+When liveness probe fails, Kubernetes like platforms restart the container.
 
 ### Readiness probe