Move and improve debug/warn docs

src/client/Client.js

@@ -270,3 +270,15 @@ class Client extends EventEmitter {
 }
 
 module.exports = Client;
+
+/**
+ * Emitted for general warnings
+ * @event Client#warn
+ * @param {string} The warning
+ */
+
+/**
+ * Emitted for general debugging information
+ * @event Client#debug
+ * @param {string} The debug information
+ */