solidified list of metrics interfaces (#2188)

prebid-server/features/pbs-feature-idx.md

@@ -53,6 +53,6 @@ title: Prebid Server | Features
 | Analytics | module support | Allows developers to plug in a [custom analytics adapter](https://github.com/prebid/prebid-server/blob/master/docs/developers/add-new-analytics-module.md). | <img src="/assets/images/icons/icon-check-green.png" width="30"> | <img src="/assets/images/icons/icon-check-green.png" width="30"> |
 | [Troubleshooting](/troubleshooting/pbs-troubleshooting.html) | test flag | Accepts the OpenRTB 'test' flag, emitting additional debug info on responses. | <img src="/assets/images/icons/icon-check-green.png" width="30"> | <img src="/assets/images/icons/icon-check-green.png" width="30"> |
 | Troubleshooting | debug flag | Accepts the ext.prebid.debug flag, emitting additional debug info on responses. | | <img src="/assets/images/icons/icon-check-green.png" width="30"> |
-| Operations | core metrics | Emits detailed operational metrics to back-end systems such as Graphite, Influx, etc. | <img src="/assets/images/icons/icon-check-green.png" width="30"> | <img src="/assets/images/icons/icon-check-green.png" width="30"> |
+| Operations | core metrics | Emits detailed operational metrics to back-end systems: Graphite, Influx, and Prometheus | <img src="/assets/images/icons/icon-check-green.png" width="30"> | <img src="/assets/images/icons/icon-check-green.png" width="30"> |
 | Operations | circuit breaker | Protects system performance during fault scenarios by detecting problems with external and internal endpoints, turning them off temporarily when a problem occurs. | | <img src="/assets/images/icons/icon-check-green.png" width="30"> |
 | Operations | [server default request](/prebid-server/features/pbs-default-request.html) | Support global defaults for incoming requests. | <img src="/assets/images/icons/icon-check-green.png" width="30"> | |