Update environments.md

Author: Rick-Anderson

aspnetcore/fundamentals/environments.md

@@ -29,7 +29,7 @@ To determine the runtime environment, ASP.NET Core reads from the following envi
 
 * <xref:Microsoft.Extensions.Hosting.Environments.Development> : The [launchSettings.json](#lsj) file sets `ASPNETCORE_ENVIRONMENT` to `Development` on the local machine.
 * <xref:Microsoft.Extensions.Hosting.Environments.Staging>
-* <xref:Microsoft.Extensions.Hosting.Environments.Production> : When the default if `DOTNET_ENVIRONMENT` and `ASPNETCORE_ENVIRONMENT` have not been set.
+* <xref:Microsoft.Extensions.Hosting.Environments.Production> : The default if `DOTNET_ENVIRONMENT` and `ASPNETCORE_ENVIRONMENT` have not been set.
 
 The following code: