Fix documentation of max job size
Fix documentation of max job size

Below is a patch for protocol.txt, which fixes a couple references to
max job size as 2**16:

diditaxi/beanstalkd,wyzssw/beanstalkd,bmhatfield/beanstalkd,tdg5/beanstalkd,qbdsoft/beanstalkd,potatosalad/beanstalkd,Qihoo360/beanstalkd-win,amyvmiwei/beanstalkd,amyvmiwei/beanstalkd,orangeholic/beanstalkd,lzpfmh/beanstalkd,mickeyouyou/beanstalkd,cgvarela/beanstalkd,PhillipMwaniki/beanstalkd,wfxiang08/beanstalkd,mobliyishengyuan/beanstalkd,handautsav/beanstalkd,aidaima/beanstalkd,JensRantil/beanstalkd,JensRantil/beanstalkd,aidaima/beanstalkd,naderman/beanstalkd,lzpfmh/beanstalkd,r3jack/beanstalkd,tdg5/beanstalkd,cgvarela/beanstalkd,wfxiang08/beanstalkd,wyzssw/beanstalkd,bmhatfield/beanstalkd,pinguo-xudianyang/beanstalkd,justintung/beanstalkd,ifduyue/beanstalkd,qbdsoft/beanstalkd,LomoX-Offical/beanstalkd-win,orangeholic/beanstalkd,CompendiumSoftware/beanstalkd,kr/beanstalkd,naderman/beanstalkd,davies/beanstalkd,yetone/beanstalkd,mickeyouyou/beanstalkd,PhillipMwaniki/beanstalkd,LomoX-Offical/beanstalkd-win,mobliyishengyuan/beanstalkd,yetone/beanstalkd,kr/beanstalkd,Qihoo360/beanstalkd-win,naderman/beanstalkd,potatosalad/beanstalkd,ifduyue/beanstalkd,r3jack/beanstalkd,justintung/beanstalkd,davies/beanstalkd,pinguo-xudianyang/beanstalkd,diditaxi/beanstalkd,handautsav/beanstalkd,CompendiumSoftware/beanstalkd