added note about portrait orientation on iPhone
added note about portrait orientation on iPhone

Jawbone/apptentive-ios,apptentive/apptentive-ios,hibu/apptentive-ios,hibu/apptentive-ios,apptentive/apptentive-ios,hibu/apptentive-ios,apptentive/apptentive-ios,Jawbone/apptentive-ios