clarify instrumentation key environment variable usage further

Author: mrbullwinkle

articles/azure-monitor/app/asp-net-core.md

@@ -105,9 +105,9 @@ The [Application Insights SDK for ASP.NET Core](https://nuget.org/packages/Micro
 
     * `SET APPINSIGHTS_INSTRUMENTATIONKEY=putinstrumentationkeyhere`
 
-    * `APPINSIGHTS_INSTRUMENTATIONKEY` specifies the instrumentation key for applications deployed to [Azure Web Apps](https://docs.microsoft.com/azure/azure-monitor/app/azure-web-apps?tabs=net).
+    * `APPINSIGHTS_INSTRUMENTATIONKEY` is typically used in [Azure Web Apps](https://docs.microsoft.com/azure/azure-monitor/app/azure-web-apps?tabs=net), but can also be used in all places where this SDK is supported. (If you are doing codeless web app monitoring, this format is required if you aren't using connection strings.)
 
-    In lieu of setting instrumentation keys you can now also use [Connection Strings](https://docs.microsoft.com/azure/azure-monitor/app/sdk-connection-string?tabs=net)
+    In lieu of setting instrumentation keys you can now also use [Connection Strings](https://docs.microsoft.com/azure/azure-monitor/app/sdk-connection-string?tabs=net).
 
     > [!NOTE]
     > An instrumentation key specified in code wins over the environment variable `APPINSIGHTS_INSTRUMENTATIONKEY`, which wins over other options.