add remark about async false

Author: platzhersh

README.md

@@ -26,6 +26,7 @@ Version history
 * add `package.json`
 * add `server.js`
 * you can now run pacman running an express JS server, using `npm start`
+* don't use ajax `async: false` anymore to load map config, since it has been marked as deprecated
 
 *Version 0.93 - 8.1.2020*
 * add `ads.txt`