Document undocumented LogFilter feature
Document undocumented LogFilter feature

This fixes github issue #1671.

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