chore(docs): use done() in gen-docs.js

Author: IgorMinar

docs/src/gen-docs.js

@@ -32,7 +32,7 @@ writer.makeDir('build/docs/', true).then(function() {
   });
 }).then(function printStats() {
   console.log('DONE. Generated ' + docs.length + ' pages in ' + (now()-start) + 'ms.' );
-});
+}).done();
 
 
 function writeTheRest(writesFuture) {