docs: update alerting with new data sources

docs/sources/alerting/rules.md

@@ -27,8 +27,7 @@ and the conditions that need to be met for the alert to change state and trigger
 ## Execution
 
 The alert rules are evaluated in the Grafana backend in a scheduler and query execution engine that is part
-of core Grafana. Only some data sources are supported right now. They include `Graphite`, `Prometheus`,
-`InfluxDB` and `OpenTSDB`.
+of core Grafana. Only some data sources are supported right now. They include `Graphite`, `Prometheus`, `InfluxDB`, `OpenTSDB`, `MySQL`, `Postgres` and `Cloudwatch`.
 
 ### Clustering
 

docs/sources/features/datasources/cloudwatch.md

@@ -169,5 +169,3 @@ Amazon provides 1 million CloudWatch API requests each month at no additional ch
 it costs $0.01 per 1,000 GetMetricStatistics or ListMetrics requests. For each query Grafana will
 issue a GetMetricStatistics request and every time you pick a dimension in the query editor
 Grafana will issue a ListMetrics request.
-
-