Expand documentation of magic prefix in REST API's JSON responses
Expand documentation of magic prefix in REST API's JSON responses

Add a sentence explaining that the prefix is needed in order to
prevent XSSI attacks.

Change-Id: Ib22dc269c6f11e9ec0d31b84cd284e58a79b41c5

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