Add documentation of review category strategy username preference
Add documentation of review category strategy username preference

The USERNAME option was added, but was not mentioned in the
documentation.

Change-Id: Icd13f6a17de1717ab0952e46b17e2872c9e8ca14

hdost/gerrit,netroby/gerrit,renchaorevee/gerrit,Distrotech/gerrit,Team-OctOS/host_gerrit,supriyantomaftuh/gerrit,hdost/gerrit,thesamet/gerrit,jackminicloud/test,thinkernel/gerrit,Overruler/gerrit,Seinlin/gerrit,Team-OctOS/host_gerrit,GerritCodeReview/gerrit,thinkernel/gerrit,gerrit-review/gerrit,thinkernel/gerrit,jackminicloud/test,Seinlin/gerrit,dwhipstock/gerrit,WANdisco/gerrit,pkdevbox/gerrit,supriyantomaftuh/gerrit,MerritCR/merrit,supriyantomaftuh/gerrit,Seinlin/gerrit,Team-OctOS/host_gerrit,renchaorevee/gerrit,gcoders/gerrit,Distrotech/gerrit,thesamet/gerrit,midnightradio/gerrit,quyixia/gerrit,joshuawilson/merrit,gerrit-review/gerrit,supriyantomaftuh/gerrit,midnightradio/gerrit,jackminicloud/test,gerrit-review/gerrit,renchaorevee/gerrit,thesamet/gerrit,gerrit-review/gerrit,gerrit-review/gerrit,MerritCR/merrit,renchaorevee/gerrit,gerrit-review/gerrit,Distrotech/gerrit,joshuawilson/merrit,TonyChai24/test,quyixia/gerrit,joshuawilson/merrit,qtproject/qtqa-gerrit,Seinlin/gerrit,pkdevbox/gerrit,joshuawilson/merrit,GerritCodeReview/gerrit,jackminicloud/test,hdost/gerrit,pkdevbox/gerrit,netroby/gerrit,Team-OctOS/host_gerrit,supriyantomaftuh/gerrit,gcoders/gerrit,gcoders/gerrit,Team-OctOS/host_gerrit,hdost/gerrit,TonyChai24/test,Overruler/gerrit,thesamet/gerrit,pkdevbox/gerrit,MerritCR/merrit,supriyantomaftuh/gerrit,WANdisco/gerrit,dwhipstock/gerrit,qtproject/qtqa-gerrit,thesamet/gerrit,thinkernel/gerrit,quyixia/gerrit,Seinlin/gerrit,quyixia/gerrit,dwhipstock/gerrit,quyixia/gerrit,Distrotech/gerrit,gerrit-review/gerrit,Seinlin/gerrit,anminhsu/gerrit,renchaorevee/gerrit,midnightradio/gerrit,midnightradio/gerrit,anminhsu/gerrit,qtproject/qtqa-gerrit,Team-OctOS/host_gerrit,dwhipstock/gerrit,pkdevbox/gerrit,quyixia/gerrit,Overruler/gerrit,Overruler/gerrit,MerritCR/merrit,jackminicloud/test,netroby/gerrit,pkdevbox/gerrit,joshuawilson/merrit,TonyChai24/test,MerritCR/merrit,gcoders/gerrit,qtproject/qtqa-gerrit,anminhsu/gerrit,Seinlin/gerrit,netroby/gerrit,hdost/gerrit,joshuawilson/merrit,MerritCR/merrit,thinkernel/gerrit,joshuawilson/merrit,MerritCR/merrit,gcoders/gerrit,qtproject/qtqa-gerrit,gcoders/gerrit,midnightradio/gerrit,anminhsu/gerrit,WANdisco/gerrit,WANdisco/gerrit,TonyChai24/test,netroby/gerrit,supriyantomaftuh/gerrit,WANdisco/gerrit,netroby/gerrit,gcoders/gerrit,pkdevbox/gerrit,Overruler/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,thesamet/gerrit,anminhsu/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,hdost/gerrit,renchaorevee/gerrit,hdost/gerrit,dwhipstock/gerrit,netroby/gerrit,dwhipstock/gerrit,Distrotech/gerrit,joshuawilson/merrit,thinkernel/gerrit,Distrotech/gerrit,Team-OctOS/host_gerrit,MerritCR/merrit,GerritCodeReview/gerrit,quyixia/gerrit,TonyChai24/test,jackminicloud/test,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,thinkernel/gerrit,jackminicloud/test,WANdisco/gerrit,renchaorevee/gerrit,Overruler/gerrit,GerritCodeReview/gerrit,anminhsu/gerrit,anminhsu/gerrit,dwhipstock/gerrit,TonyChai24/test,midnightradio/gerrit,thesamet/gerrit,Distrotech/gerrit,TonyChai24/test