Update resource-name-rules.md

added Prometheus

Author: nolavime

articles/azure-resource-manager/management/resource-name-rules.md

@@ -492,6 +492,7 @@ In the following tables, the term alphanumeric refers to:
 > | scheduledQueryRules | resource group | 1-260 | Can't use:<br>`*<>%{}&:\\?/#|` or control characters <br><br>Can't end with space or period.  |
 > | metricAlerts | resource group | 1-260 | Can't use:<br>`*#&+:<>?@%{}\/|` or control characters <br><br>Can't end with space or period.  |
 > | activityLogAlerts | resource group | 1-260 | Can't use:<br>`<>*%{}&:\\?+/#|` or control characters <br><br>Can't end with space or period.  |
+> | PrometheusAlerts | resource group | 1-260 | Can't use:<br>`<>*%{}&:\\?+/#|` or control characters <br><br>Can't end with space or period.  |
 
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