Route with Service Tag has already been GA. (#18755)

Route with Service Tag has already been Generally available, not preview.

src/Network/Network/help/New-AzRouteConfig.md

@@ -53,7 +53,7 @@ Creates a route for a route table. (autogenerated)
 New-AzRouteConfig -AddressPrefix 10.1.0.0/16 -Name 'Route07' -NextHopIpAddress '12.0.0.5' -NextHopType 'VnetLocal'
 ```
 
-### Example 3: Create a route with a Service Tag (Public Preview)
+### Example 3: Create a route with a Service Tag
 ```powershell
 New-AzRouteConfig -Name "Route07" -AddressPrefix "AppService" -NextHopType "VirtualAppliance" -NextHopIpAddress "10.0.2.4"
 ```