Fix OAuth2 Example Code (#1844)

The token and token type are backwards. When using the current code, it will set the Authorization Header to "[token] Bearer". Switching them around fixes the issue and sets the Authorization Header to "Bearer [token]".

Author: jaredwaller

docs/authenticators.md

@@ -65,7 +65,7 @@ For example:
 
 ```csharp
 client.Authenticator = new OAuth2AuthorizationRequestHeaderAuthenticator(
-    "Bearer", token
+    token, "Bearer"
 );
 ```