Improve alt-text for hosting spectrum diagram

Updated alt-text for application hosting spectrum image.

Author: JamesJBarnett

learn-pr/wwl-azure/describe-azure-compute-networking-services/includes/7-describe-application-hosting-options.md

@@ -2,7 +2,7 @@ If you need to host your application on Azure, you might initially turn to a vir
 
 There are other hosting options that you can use with Azure, including Azure App Service.
 
-:::image type="content" source="../media/application-hosting-spectrum.png" alt-text="Hosting spectrum from VMs with more control, to containers, to App Service with less operational effort.":::
+:::image type="content" source="../media/application-hosting-spectrum.png" alt-text="Diagram showing hosting spectrum from VMs with more control, to containers, to App Service with less operational effort.":::
 
 ## Azure App Service