Fix reload after changes in the main app bundle

Summary: Fixed automatic reloading on changes while "yarn start"

Reviewed By: mweststrate

Differential Revision: D20691166

fbshipit-source-id: 78b01a3c5e4a6da1537f2230411069e04ebbc81e

desktop/scripts/start-dev-server.ts

@@ -182,7 +182,7 @@ async function addWebsocket(server: http.Server) {
     const watchman = new Watchman(path.resolve(__dirname, '..'));
     await watchman.initialize();
     await Promise.all(
-      ['src', 'pkg', 'doctor'].map((dir) =>
+      ['app', 'pkg', 'doctor'].map((dir) =>
         watchman.startWatchFiles(
           dir,
           () => {