fixing a typo from the sms filtering example
fixing a typo from the sms filtering example

twilio/twilio-php,sayan801/twilio-php,pablophg/twilio-php,FTrubitz/twilio-php,Git-Host/twilio-php,beachboysapp/urgentMe,MartinAmps/twilio-php,javierwilson/twilio-php,beachboysapp/urgentMe,achoe/twilio-php