Improve the wrapper_mappings explanation.
Improve the wrapper_mappings explanation.

weixing2014/simple_form-bootstrap,weixing2014/simple_form-bootstrap,npy179/simple_form-bootstrap,npy179/simple_form-bootstrap,vaishalitekale/simple_form-bootstrap,rafaelfranca/simple_form-bootstrap,vaishalitekale/simple_form-bootstrap,weixing2014/simple_form-bootstrap,vaishalitekale/simple_form-bootstrap,rafaelfranca/simple_form-bootstrap,rafaelfranca/simple_form-bootstrap,npy179/simple_form-bootstrap