CodeGen from PR 17162 in Azure/azure-rest-api-specs

[Hub Generated] Review request for Microsoft.AlertsManagement to add version stable/2021-08-08 (#17162)

* Adds base for updating Microsoft.AlertsManagement from version preview/2021-08-08-preview to version 2021-08-08

* Updates readme

* Updates API version in new specs and examples

* 1. added input files to new tag
2. changed alerts management client tag to the new tag

Co-authored-by: Liran Englender <lienglender@microsoft.com>

Author: SDKAuto