Updated key with text in BotService.cs to solve gitleak issue

Author: Ravikumar Akuthota

SfChatDemo/SfChatDemo/View/BotService.cs

@@ -36,7 +36,7 @@ public class BotService
         /// <summary>
         /// Direct line key to establish connection to syncfusion bot.
         /// </summary>
-        private string directLineKey = "use your own key";
+        private string directLineKey = "use your own key.";
 
         /// <summary>
         /// water mark used to get newly added message or actvity.