Docs fix for getProject (#428)

Author: monkbroc

lib/GitHub.js

@@ -117,7 +117,7 @@ class GitHub {
    /**
     * Create a new Project wrapper
     * @param {string} id - the id of the project
-    * @return {Markdown}
+    * @return {Project}
     */
    getProject(id) {
       return new Project(id, this.__auth, this.__apiBase);