Fixing spelling mistake

Author: mathewc

src/WebJobs.Script.WebHost/WebHooks/WebJobsSdkExtensionHookProvider.cs

@@ -40,7 +40,7 @@ public Uri GetUrl(IExtensionConfigProvider extension)
             var handler = extension as HttpHandler;
             if (handler == null)
             {
-                throw new InvalidOperationException($"Extension must implemnent IAsyncConverter<HttpRequestMessage, HttpResponseMessage> in order to receive hooks");
+                throw new InvalidOperationException($"Extension must implement IAsyncConverter<HttpRequestMessage, HttpResponseMessage> in order to receive webhooks");
             }
 
             string name = extensionType.Name;