Update monitor to latest package 2021-09 (Azure#16746)

Author: herreraj-ms

specification/monitor/resource-manager/readme.md

@@ -35,7 +35,7 @@ title: MonitorManagementClient
 ``` yaml
 description: Monitor Management Client
 openapi-type: arm
-tag: package-2021-08
+tag: package-2021-09
 
 directive:
   - suppress: Example Validations
@@ -73,12 +73,6 @@ input-file:
 - Microsoft.Insights/stable/2021-04-01/dataCollectionRules_API.json
 ```
 
-``` yaml
-description: Monitor Management Client
-openapi-type: arm
-tag: package-2021-08
-```
-
 ### Tag: package-2021-09-01-only
 
 These settings apply only when `--tag=package-2021-09-01-only` is specified on the command line.