📒Update README with more information

Author: tam7t

README.md

@@ -1,6 +1,31 @@
 # go-metrics-stackdriver
+[![godoc](https://godoc.org/github.com/google/go-metrics-stackdriver?status.svg)](http://godoc.org/github.com/google/go-metrics-stackdriver)
 
 This library provides a stackdriver sink for applications instrumented with the
 [go-metrics](https://github.com/armon/go-metrics) library.
 
+## Details
+
+[stackdriver.NewSink](https://godoc.org/github.com/google/go-metrics-stackdriver#NewSink)'s return value satisfies the go-metrics library's [MetricSink](https://godoc.org/github.com/armon/go-metrics#MetricSink) interface. When providing a `stackdriver.Sink` to libraries and applications instrumented against `MetricSink`, the metrics will be aggregated within this library and written to stackdriver as [Generic Task](https://cloud.google.com/monitoring/api/resources#tag_generic_task) timeseries metrics.
+
+## Example
+
+```go
+import "github.com/google/go-metrics-stackdriver"
+...
+client, _ := monitoring.NewMetricClient(context.Background())
+ss := stackdriver.NewSink(60*time.Second, &stackdriver.TaskInfo{
+  ProjectID: projectID,
+  Location:  "us-east1-c",
+  Job:       "example-app",
+}, client)
+...
+ss.SetGauge([]string{"foo"}, 42)
+ss.IncrCounter([]string{"baz"}, 1)
+ss.AddSample([]string{"method", "const"}, 200)
+```
+
+The [full example](example/main.go) can be run from a cloud shell console to test how metrics are collected and displayed.
+
+
 __This is not an officially supported Google product.__