Update header_rewrite docs to be closer to reality
Update header_rewrite docs to be closer to reality

bryancall/trafficserver,clearswift/trafficserver,rahmalik/trafficserver,PSUdaemon/trafficserver,rahmalik/trafficserver,duke8253/trafficserver,reveller/trafficserver,reveller/trafficserver,pbchou/trafficserver,SolidWallOfCode/trafficserver,clearswift/trafficserver,pbchou/trafficserver,dyrock/trafficserver,pbchou/trafficserver,pbchou/trafficserver,PSUdaemon/trafficserver,bryancall/trafficserver,clearswift/trafficserver,taoyunxing/trafficserver,rahmalik/trafficserver,SolidWallOfCode/trafficserver,taoyunxing/trafficserver,chitianhao/trafficserver,chenglongwei/trafficserver,rpufky/trafficserver,duke8253/trafficserver,rpufky/trafficserver,chitianhao/trafficserver,chitianhao/trafficserver,chitianhao/trafficserver,rpufky/trafficserver,PSUdaemon/trafficserver,davidbz/trafficserver,rpufky/trafficserver,reveller/trafficserver,taoyunxing/trafficserver,reveller/trafficserver,PSUdaemon/trafficserver,taoyunxing/trafficserver,chenglongwei/trafficserver,taoyunxing/trafficserver,dyrock/trafficserver,persiaAziz/trafficserver,duke8253/trafficserver,duke8253/trafficserver,reveller/trafficserver,davidbz/trafficserver,clearswift/trafficserver,rpufky/trafficserver,persiaAziz/trafficserver,reveller/trafficserver,rahmalik/trafficserver,persiaAziz/trafficserver,taoyunxing/trafficserver,dyrock/trafficserver,rahmalik/trafficserver,davidbz/trafficserver,dyrock/trafficserver,chenglongwei/trafficserver,chitianhao/trafficserver,chenglongwei/trafficserver,davidbz/trafficserver,bryancall/trafficserver,duke8253/trafficserver,clearswift/trafficserver,rpufky/trafficserver,pbchou/trafficserver,persiaAziz/trafficserver,clearswift/trafficserver,persiaAziz/trafficserver,SolidWallOfCode/trafficserver,chenglongwei/trafficserver,PSUdaemon/trafficserver,rpufky/trafficserver,PSUdaemon/trafficserver,duke8253/trafficserver,vmamidi/trafficserver,chitianhao/trafficserver,reveller/trafficserver,chitianhao/trafficserver,rahmalik/trafficserver,SolidWallOfCode/trafficserver,rpufky/trafficserver,reveller/trafficserver,rahmalik/trafficserver,persiaAziz/trafficserver,taoyunxing/trafficserver,bryancall/trafficserver,persiaAziz/trafficserver,vmamidi/trafficserver,persiaAziz/trafficserver,bryancall/trafficserver,rahmalik/trafficserver,clearswift/trafficserver,chenglongwei/trafficserver,chenglongwei/trafficserver,bryancall/trafficserver,dyrock/trafficserver,clearswift/trafficserver,davidbz/trafficserver,PSUdaemon/trafficserver,taoyunxing/trafficserver,vmamidi/trafficserver,SolidWallOfCode/trafficserver,SolidWallOfCode/trafficserver,taoyunxing/trafficserver,clearswift/trafficserver,dyrock/trafficserver,rpufky/trafficserver,vmamidi/trafficserver,PSUdaemon/trafficserver,pbchou/trafficserver,davidbz/trafficserver,vmamidi/trafficserver,chenglongwei/trafficserver,reveller/trafficserver,PSUdaemon/trafficserver,rahmalik/trafficserver,vmamidi/trafficserver,SolidWallOfCode/trafficserver,duke8253/trafficserver,dyrock/trafficserver