exporter/metric/prometheus: fix incorrect code format comments for In…

…stallNewPipeline (open-telemetry#482)

Co-authored-by: Rahul Patel <[email protected]>

exporter/metric/prometheus/prometheus.go

@@ -118,13 +118,15 @@ func NewRawExporter(config Config) (*Exporter, error) {
 
 // InstallNewPipeline instantiates a NewExportPipeline and registers it globally.
 // Typically called as:
-// pipeline, hf, err := prometheus.InstallNewPipeline(prometheus.Config{...})
-// if err != nil {
-// ...
-// }
-// http.HandleFunc("/metrics", hf)
-// defer pipeline.Stop()
-// ... Done
+//
+// pipeline, hf, err := prometheus.InstallNewPipeline(prometheus.Config{...})
+//
+// if err != nil {
+// ...
+// }
+// http.HandleFunc("/metrics", hf)
+// defer pipeline.Stop()
+// ... Done
 func InstallNewPipeline(config Config) (*push.Controller, http.HandlerFunc, error) {
  controller, hf, err := NewExportPipeline(config)
  if err != nil {