Add request for sample queries (#1608)

CONTRIBUTING.md

@@ -11,6 +11,7 @@ Output plugins READMEs are less structured,
 but any information you can provide on how the data will look is appreciated.
 See the [OpenTSDB output](https://github.com/influxdata/telegraf/tree/master/plugins/outputs/opentsdb)
 for a good example.
+1. **Optional:** Help users of your plugin by including example queries for populating dashboards. Include these sample queries in the `README.md` for the plugin.
 1. **Optional:** Write a [tickscript](https://docs.influxdata.com/kapacitor/v1.0/tick/syntax/) for your plugin and add it to [Kapacitor](https://github.com/influxdata/kapacitor/tree/master/examples/telegraf). Or mention @jackzampolin in a PR comment with some common queries that you would want to alert on and he will write one for you.
 
 ## GoDoc

plugins/inputs/EXAMPLE_README.md

@@ -28,6 +28,14 @@ The example plugin gathers metrics about example things
 - measurement2 has the following tags:
     - tag3
     
+### Sample Queries:
+
+These are some useful queries (to generate dashboards or other) to run against data from this plugin:
+
+```
+SELECT max(field1), mean(field1), min(field1) FROM measurement1 WHERE tag1=bar AND time > now() - 1h GROUP BY tag
+```
+
 ### Example Output:
 
 ```

plugins/inputs/mock_Plugin.go

@@ -6,10 +6,22 @@ import (
 	"github.com/stretchr/testify/mock"
 )
 
+// MockPlugin struct should be named the same as the Plugin
 type MockPlugin struct {
 	mock.Mock
 }
 
+// Description will appear directly above the plugin definition in the config file
+func (m *MockPlugin) Description() string {
+	return `This is an example plugin`
+}
+
+// SampleConfig will populate the sample configuration portion of the plugin's configuration
+func (m *MockPlugin) SampleConfig() string {
+	return `  sampleVar = 'foo'`
+}
+
+// Gather defines what data the plugin will gather.
 func (m *MockPlugin) Gather(_a0 telegraf.Accumulator) error {
 	ret := m.Called(_a0)