Update metrics documentation with the prefix (#1112)

Metrics have the component name as the prefix.  Added those to the documentation.

docs/metrics.md

@@ -16,18 +16,18 @@ The following chains metrics are also available at `tekton-chains-metrics` servi
 
 | Name | Type | Description |
 |-----------------------------------------------------------------------------------------| ----------- | ----------- |
-| `pipelinerun_sign_created_total` | Counter | Total number of signed messages for pipelineruns |
-| `pipelinerun_payload_uploaded_total` | Counter | Total number of uploaded payloads for pipelineruns |
-| `pipelinerun_payload_stored_total` | Counter | Total number of stored payloads for pipelineruns |
-| `pipelinerun_marked_signed_total` | Counter | Total number of objects marked as signed for pipelineruns |
-| `taskrun_sign_created_total` | Counter | Total number of signed messages for taskruns |
-| `taskrun_payload_uploaded_total` | Counter | Total number of uploaded payloads for taskruns |
-| `taskrun_payload_stored_total` | Counter | Total number of stored payloads for taskruns |
-| `taskrun_marked_signed_total` | Counter | Total number of objects marked as signed for taskruns |
+| `watcher_pipelinerun_sign_created_total` | Counter | Total number of signed messages for pipelineruns |
+| `watcher_pipelinerun_payload_uploaded_total` | Counter | Total number of uploaded payloads for pipelineruns |
+| `watcher_pipelinerun_payload_stored_total` | Counter | Total number of stored payloads for pipelineruns |
+| `watcher_pipelinerun_marked_signed_total` | Counter | Total number of objects marked as signed for pipelineruns |
+| `watcher_taskrun_sign_created_total` | Counter | Total number of signed messages for taskruns |
+| `watcher_taskrun_payload_uploaded_total` | Counter | Total number of uploaded payloads for taskruns |
+| `watcher_taskrun_payload_stored_total` | Counter | Total number of stored payloads for taskruns |
+| `watcher_taskrun_marked_signed_total` | Counter | Total number of objects marked as signed for taskruns |
 
 To access the chains metrics, use the following commands:
 ```shell
 kubectl port-forward -n tekton-chains service/tekton-chains-metrics 9090
 ```
 
-And then check that changes have been applied to metrics coming from [http://127.0.0.1:9090/metrics](http://127.0.0.1:9090/metrics)
+And then check that changes have been applied to metrics coming from [http://127.0.0.1:9090/metrics](http://127.0.0.1:9090/metrics)