Added a note to the README of the 'Custom Method' example

Author: AdrienCastex

examples/v2/customMethod/README.md

@@ -6,3 +6,5 @@ This example focus on the `TRACE` method, to send to a remote user all actions t
 It uses the headers `Trace-Depth`, `Trace-Separator` and `Trace-Method` to customize the answer and the observed resources.
 
 The `ts` file and the `js` file are the same thing. The `js` file displays the example in JavaScript while the `ts` file displays the example in TypeScript.
+
+Note : The methods which can be added are limited to [the supported methods](https://nodejs.org/api/http.html#http_http_methods) in the `http` module.