Kestrel topic updates (#12529)

aspnetcore/fundamentals/servers/kestrel.md

@@ -155,6 +155,12 @@ The Kestrel web server has constraint configuration options that are especially
 
 Set constraints on the <xref:Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerOptions.Limits> property of the <xref:Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerOptions> class. The `Limits` property holds an instance of the <xref:Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerLimits> class.
 
+The following examples use the <xref:Microsoft.AspNetCore.Server.Kestrel.Core> namespace:
+
+```csharp
+using Microsoft.AspNetCore.Server.Kestrel.Core;
+```
+
 ### Keep-alive timeout
 
 <xref:Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerLimits.KeepAliveTimeout>
@@ -644,7 +650,7 @@ In the following *appsettings.json* example:
       "Url": "https://localhost:5002",
       "Certificate": {
         "Subject": "<subject; required>",
-        "Store": "<certificate store; defaults to My>",
+        "Store": "<certificate store; required>",
         "Location": "<location; defaults to CurrentUser>",
         "AllowInvalid": "<true or false; defaults to false>"
       }
@@ -677,7 +683,7 @@ An alternative to using **Path** and **Password** for any certificate node is to
 ```json
 "Default": {
   "Subject": "<subject; required>",
-  "Store": "<cert store; defaults to My>",
+  "Store": "<cert store; required>",
   "Location": "<location; defaults to CurrentUser>",
   "AllowInvalid": "<true or false; defaults to false>"
 }

aspnetcore/fundamentals/servers/kestrel/samples/2.x/KestrelSample/Startup.cs

@@ -9,7 +9,6 @@ using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Server.Kestrel.Core;
 using Microsoft.AspNetCore.Server.Kestrel.Core.Features;
-using Microsoft.Extensions.Logging;
 
 namespace KestrelSample
 {