update main.d.ts

typescript/types/main.d.ts

@@ -12538,6 +12538,14 @@ declare const global: {
   [key: string]: any;
 }
 
+/**
+ * A reference to the global scope, where everything is defined.
+ * This is identical to `global` but was introduced in the ECMAScript spec.
+ * @returns {any} The global scope
+ * @url http://www.espruino.com/Reference#l__global_globalThis
+ */
+// globalThis - builtin
+
 /**
  * A variable containing the arguments given to the function:
  * ```