[Insights] Include notice about renaming Set-AzureRmDiagnosticSettings to Update-AzureRmDiagnosticSettings in the upcoming breaking changes doc

Author: vcanaa

src/ResourceManager/Insights/documentation/upcoming-breaking-changes.md

@@ -141,4 +141,15 @@
     write-host "Unit: $s21.Unit"
     write-host "Data: $s21.Data"
 
+    ```
+
+  **Set-AzureRmDiagnosticSettings**
+    - The command is going to be renamed to Update-AzureRmDiagnsoticSettings
+
+    ```powershell
+    # Old
+    # Set-AzureRmDiagnosticSettings
+
+    # New
+    # Update-AzureRmDiagnosticSettings
     ```