Rename extra

Author: davidgasquez

README.md

@@ -22,7 +22,7 @@ import bufflog
 
 bufflog = bufflog.get_logger(__name__)
 
-bufflog.debug('Hello debug', extra={"some":"stuff"})
+bufflog.debug('Hello debug', context={"some":"stuff"})
 bufflog.info('Hello info')
 bufflog.error('Hello error')
 bufflog.critical('Hello critical')