Revise README.md.

Author: Baliedge

promexporter/README.md

@@ -1,8 +1,8 @@
 # Prometheus Groupcache Exporter
 
-This exporter extracts statistics from groupcache instances and exports Prometheus metrics.
+This exporter extracts statistics from group instances and exports as Prometheus metrics.
 
-# Example
+## Example
 
 ```go
 import (
@@ -20,14 +20,17 @@ prometheus.MustRegister(collector)
 group := groupcache.NewGroup("mygroup", cacheSize, getter)
 ```
 
-## Exported Metrics
+## Metrics
 
+### Exported from groupcache's `CacheStats()`
 - `groupcache_cache_bytes{group,type="main|hot"}`: Gauge of current bytes in use
 - `groupcache_cache_evictions_nonexpired_total{group,type="main|hot"}`: Count of cache evictions for non-expired keys due to memory full
 - `groupcache_cache_evictions_total{group,type="main|hot"}`: Count of cache evictions
 - `groupcache_cache_gets_total{group,type="main|hot"}`: Count of cache gets
 - `groupcache_cache_hits_total{group,type="main|hot"}`: Count of cache hits
 - `groupcache_cache_items{group,type="main|hot"}`: Gauge of current items in use
+
+### Exported from groupcache's `Stats()`
 - `groupcache_get_from_peers_latency_lower{group}`: Represent slowest duration to request value from peers
 - `groupcache_gets_total{group}`: Count of cache gets (including from peers, from either main or hot caches)
 - `groupcache_hits_total{group}`: Count of cache hits (from either main or hot caches)
@@ -39,6 +42,6 @@ group := groupcache.NewGroup("mygroup", cacheSize, getter)
 - `groupcache_peer_loads_total{group}`: Count of loads or cache hits from peers
 - `groupcache_server_requests_total{group}`: Count of gets received from peers
 
-# Attribution
+## Attribution
 
-This package source was copied from https://github.com/udhos/groupcache_exporter.  See LICENSE for MIT license details impacting the contents of this package directory in addition to the LICENSE at the root of this repo for co-existing Apache license details.
+This package source originated from https://github.com/udhos/groupcache_exporter.  See LICENSE for MIT license details impacting the contents of this package directory in addition to the LICENSE at the root of this repo for co-existing Apache license details.