changed: updated documentation for custom widgets, closes https://github.com/enketo/enketo-express/issues/68
changed: updated documentation for custom widgets, closes https://github.com/enketo/enketo-express/issues/68

enketo/enketo-express,OpenClinica/enketo-express-oc,onaio/enketo-express,onaio/enketo-express,OpenClinica/enketo-express-oc,kobotoolbox/enketo-express,OpenClinica/enketo-express-oc,enketo/enketo-express,enketo/enketo-express,kobotoolbox/enketo-express,kobotoolbox/enketo-express,kobotoolbox/enketo-express,onaio/enketo-express