These docs are for an old release.
Info on upgrading to version 2/3
monthNames 1.3
Full names of months.
Array, default:
['January', 'February', 'March', 'April', 'May', 'June', 'July',
'August', 'September', 'October', 'November', 'December']
Prior to version 1.3, this was possible by setting $.fullCalendar.monthNames