Add documentation on rule set files
Add documentation on rule set files

Add documentation describing the relevant portions of the .ruleset file
format.

Fixes #1073.

jamesqo/roslyn,dotnet/roslyn,Inverness/roslyn,gafter/roslyn,mgoertz-msft/roslyn,gafter/roslyn,doconnell565/roslyn,jhendrixMSFT/roslyn,sharadagrawal/Roslyn,antiufo/roslyn,jbhensley/roslyn,ljw1004/roslyn,lorcanmooney/roslyn,KamalRathnayake/roslyn,droyad/roslyn,leppie/roslyn,russpowers/roslyn,kuhlenh/roslyn,kuhlenh/roslyn,weltkante/roslyn,abock/roslyn,heejaechang/roslyn,balajikris/roslyn,antonssonj/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,physhi/roslyn,oocx/roslyn,danielcweber/roslyn,genlu/roslyn,KamalRathnayake/roslyn,VSadov/roslyn,vslsnap/roslyn,OmniSharp/roslyn,HellBrick/roslyn,OmarTawfik/roslyn,Hosch250/roslyn,sharadagrawal/TestProject2,3F/roslyn,jmarolf/roslyn,rchande/roslyn,YOTOV-LIMITED/roslyn,diryboy/roslyn,akrisiun/roslyn,vcsjones/roslyn,mirhagk/roslyn,xoofx/roslyn,jrharmon/roslyn,AArnott/roslyn,nemec/roslyn,VPashkov/roslyn,dpoeschl/roslyn,weltkante/roslyn,garryforreg/roslyn,pdelvo/roslyn,oberxon/roslyn,KevinRansom/roslyn,AlexisArce/roslyn,tang7526/roslyn,nagyistoce/roslyn,CyrusNajmabadi/roslyn,tannergooding/roslyn,stephentoub/roslyn,tmat/roslyn,natgla/roslyn,mattwar/roslyn,bbarry/roslyn,aanshibudhiraja/Roslyn,managed-commons/roslyn,mgoertz-msft/roslyn,AlekseyTs/roslyn,CyrusNajmabadi/roslyn,yjfxfjch/roslyn,jrharmon/roslyn,bkoelman/roslyn,AnthonyDGreen/roslyn,droyad/roslyn,aanshibudhiraja/Roslyn,xasx/roslyn,KashishArora/Roslyn,russpowers/roslyn,AlexisArce/roslyn,DustinCampbell/roslyn,aelij/roslyn,tang7526/roslyn,tsdl2013/roslyn,tsdl2013/roslyn,BugraC/roslyn,brettfo/roslyn,dotnet/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,MatthieuMEZIL/roslyn,jamesqo/roslyn,akrisiun/roslyn,tannergooding/roslyn,jaredpar/roslyn,MichalStrehovsky/roslyn,rgani/roslyn,mattscheffer/roslyn,Shiney/roslyn,AlekseyTs/roslyn,CaptainHayashi/roslyn,KashishArora/Roslyn,a-ctor/roslyn,lisong521/roslyn,pdelvo/roslyn,mattwar/roslyn,kelltrick/roslyn,AnthonyDGreen/roslyn,natgla/roslyn,pjmagee/roslyn,jeremymeng/roslyn,antiufo/roslyn,DanielRosenwasser/roslyn,pjmagee/roslyn,Giftednewt/roslyn,pjmagee/roslyn,rchande/roslyn,SeriaWei/roslyn,grianggrai/roslyn,amcasey/roslyn,robinsedlaczek/roslyn,CaptainHayashi/roslyn,rchande/roslyn,srivatsn/roslyn,drognanar/roslyn,ilyes14/roslyn,stephentoub/roslyn,enginekit/roslyn,a-ctor/roslyn,MattWindsor91/roslyn,FICTURE7/roslyn,amcasey/roslyn,physhi/roslyn,Maxwe11/roslyn,mgoertz-msft/roslyn,jhendrixMSFT/roslyn,KiloBravoLima/roslyn,Giten2004/roslyn,managed-commons/roslyn,natgla/roslyn,ErikSchierboom/roslyn,poizan42/roslyn,agocke/roslyn,grianggrai/roslyn,russpowers/roslyn,CaptainHayashi/roslyn,davkean/roslyn,DanielRosenwasser/roslyn,GuilhermeSa/roslyn,swaroop-sridhar/roslyn,mattscheffer/roslyn,oocx/roslyn,dovzhikova/roslyn,aelij/roslyn,mavasani/roslyn,FICTURE7/roslyn,VShangxiao/roslyn,poizan42/roslyn,Inverness/roslyn,nemec/roslyn,mseamari/Stuff,eriawan/roslyn,xasx/roslyn,aelij/roslyn,jkotas/roslyn,EricArndt/roslyn,evilc0des/roslyn,tmeschter/roslyn,KevinRansom/roslyn,cybernet14/roslyn,Pvlerick/roslyn,reaction1989/roslyn,reaction1989/roslyn,kelltrick/roslyn,krishnarajbb/roslyn,mseamari/Stuff,yjfxfjch/roslyn,ErikSchierboom/roslyn,moozzyk/roslyn,OmarTawfik/roslyn,tmat/roslyn,tannergooding/roslyn,bbarry/roslyn,ValentinRueda/roslyn,VShangxiao/roslyn,rgani/roslyn,ericfe-ms/roslyn,devharis/roslyn,VitalyTVA/roslyn,DanielRosenwasser/roslyn,oberxon/roslyn,diryboy/roslyn,jeremymeng/roslyn,krishnarajbb/roslyn,paulvanbrenk/roslyn,shyamnamboodiripad/roslyn,CyrusNajmabadi/roslyn,zmaruo/roslyn,garryforreg/roslyn,mattscheffer/roslyn,cybernet14/roslyn,xoofx/roslyn,robinsedlaczek/roslyn,AlekseyTs/roslyn,huoxudong125/roslyn,VitalyTVA/roslyn,jcouv/roslyn,thomaslevesque/roslyn,orthoxerox/roslyn,Pvlerick/roslyn,agocke/roslyn,MihaMarkic/roslyn-prank,panopticoncentral/roslyn,cston/roslyn,cybernet14/roslyn,brettfo/roslyn,3F/roslyn,MattWindsor91/roslyn,mseamari/Stuff,jeffanders/roslyn,VSadov/roslyn,VPashkov/roslyn,jasonmalinowski/roslyn,hanu412/roslyn,JakeGinnivan/roslyn,KevinRansom/roslyn,REALTOBIZ/roslyn,mavasani/roslyn,jbhensley/roslyn,kelltrick/roslyn,ljw1004/roslyn,tang7526/roslyn,REALTOBIZ/roslyn,MatthieuMEZIL/roslyn,v-codeel/roslyn,KashishArora/Roslyn,KirillOsenkov/roslyn,KevinH-MS/roslyn,kienct89/roslyn,weltkante/roslyn,orthoxerox/roslyn,physhi/roslyn,xasx/roslyn,cston/roslyn,antonssonj/roslyn,mavasani/roslyn,diryboy/roslyn,Hosch250/roslyn,AArnott/roslyn,krishnarajbb/roslyn,khellang/roslyn,OmarTawfik/roslyn,heejaechang/roslyn,drognanar/roslyn,VShangxiao/roslyn,leppie/roslyn,pdelvo/roslyn,jroggeman/roslyn,antonssonj/roslyn,Giten2004/roslyn,ValentinRueda/roslyn,vcsjones/roslyn,enginekit/roslyn,mirhagk/roslyn,evilc0des/roslyn,robinsedlaczek/roslyn,mmitche/roslyn,KirillOsenkov/roslyn,v-codeel/roslyn,natidea/roslyn,ljw1004/roslyn,dovzhikova/roslyn,agocke/roslyn,jcouv/roslyn,shyamnamboodiripad/roslyn,ilyes14/roslyn,jonatassaraiva/roslyn,vslsnap/roslyn,GuilhermeSa/roslyn,mmitche/roslyn,magicbing/roslyn,jeffanders/roslyn,Shiney/roslyn,wvdd007/roslyn,balajikris/roslyn,supriyantomaftuh/roslyn,abock/roslyn,Inverness/roslyn,brettfo/roslyn,RipCurrent/roslyn,hanu412/roslyn,bartdesmet/roslyn,MattWindsor91/roslyn,supriyantomaftuh/roslyn,zooba/roslyn,nemec/roslyn,ValentinRueda/roslyn,kuhlenh/roslyn,AlexisArce/roslyn,jmarolf/roslyn,huoxudong125/roslyn,AnthonyDGreen/roslyn,eriawan/roslyn,rgani/roslyn,ericfe-ms/roslyn,budcribar/roslyn,davkean/roslyn,huoxudong125/roslyn,grianggrai/roslyn,doconnell565/roslyn,balajikris/roslyn,zooba/roslyn,HellBrick/roslyn,orthoxerox/roslyn,ahmedshuhel/roslyn,KevinH-MS/roslyn,danielcweber/roslyn,KevinH-MS/roslyn,jeffanders/roslyn,chenxizhang/roslyn,antiufo/roslyn,jroggeman/roslyn,SeriaWei/roslyn,VitalyTVA/roslyn,Giftednewt/roslyn,swaroop-sridhar/roslyn,AmadeusW/roslyn,sharadagrawal/Roslyn,moozzyk/roslyn,kienct89/roslyn,ahmedshuhel/roslyn,yjfxfjch/roslyn,bartdesmet/roslyn,jonatassaraiva/roslyn,jonatassaraiva/roslyn,bkoelman/roslyn,JakeGinnivan/roslyn,jhendrixMSFT/roslyn,dpoeschl/roslyn,chenxizhang/roslyn,panopticoncentral/roslyn,AmadeusW/roslyn,tvand7093/roslyn,KiloBravoLima/roslyn,YOTOV-LIMITED/roslyn,zmaruo/roslyn,panopticoncentral/roslyn,basoundr/roslyn,nguerrera/roslyn,mirhagk/roslyn,GuilhermeSa/roslyn,akrisiun/roslyn,vslsnap/roslyn,TyOverby/roslyn,thomaslevesque/roslyn,genlu/roslyn,ahmedshuhel/roslyn,swaroop-sridhar/roslyn,Shiney/roslyn,FICTURE7/roslyn,sharwell/roslyn,mattwar/roslyn,paulvanbrenk/roslyn,wvdd007/roslyn,eriawan/roslyn,vcsjones/roslyn,sharwell/roslyn,doconnell565/roslyn,shyamnamboodiripad/roslyn,genlu/roslyn,v-codeel/roslyn,zmaruo/roslyn,cston/roslyn,amcasey/roslyn,MichalStrehovsky/roslyn,MatthieuMEZIL/roslyn,garryforreg/roslyn,khyperia/roslyn,nguerrera/roslyn,sharadagrawal/TestProject2,TyOverby/roslyn,Pvlerick/roslyn,MihaMarkic/roslyn-prank,DustinCampbell/roslyn,magicbing/roslyn,EricArndt/roslyn,michalhosala/roslyn,jbhensley/roslyn,jasonmalinowski/roslyn,taylorjonl/roslyn,a-ctor/roslyn,MihaMarkic/roslyn-prank,stebet/roslyn,OmniSharp/roslyn,danielcweber/roslyn,dpoeschl/roslyn,3F/roslyn,srivatsn/roslyn,AmadeusW/roslyn,tmeschter/roslyn,mmitche/roslyn,VSadov/roslyn,lorcanmooney/roslyn,aanshibudhiraja/Roslyn,SeriaWei/roslyn,michalhosala/roslyn,sharadagrawal/TestProject2,KiloBravoLima/roslyn,kienct89/roslyn,Hosch250/roslyn,ilyes14/roslyn,droyad/roslyn,basoundr/roslyn,jamesqo/roslyn,drognanar/roslyn,OmniSharp/roslyn,Giftednewt/roslyn,VPashkov/roslyn,xoofx/roslyn,TyOverby/roslyn,lorcanmooney/roslyn,KamalRathnayake/roslyn,leppie/roslyn,devharis/roslyn,jmarolf/roslyn,moozzyk/roslyn,Giten2004/roslyn,poizan42/roslyn,bbarry/roslyn,JakeGinnivan/roslyn,stebet/roslyn,budcribar/roslyn,dovzhikova/roslyn,tvand7093/roslyn,tmeschter/roslyn,lisong521/roslyn,khyperia/roslyn,heejaechang/roslyn,lisong521/roslyn,KirillOsenkov/roslyn,khyperia/roslyn,michalhosala/roslyn,yeaicc/roslyn,enginekit/roslyn,bkoelman/roslyn,bartdesmet/roslyn,natidea/roslyn,reaction1989/roslyn,AArnott/roslyn,dotnet/roslyn,evilc0des/roslyn,Maxwe11/roslyn,davkean/roslyn,RipCurrent/roslyn,hanu412/roslyn,managed-commons/roslyn,devharis/roslyn,nguerrera/roslyn,sharwell/roslyn,nagyistoce/roslyn,REALTOBIZ/roslyn,gafter/roslyn,magicbing/roslyn,jroggeman/roslyn,tvand7093/roslyn,abock/roslyn,yeaicc/roslyn,zooba/roslyn,jcouv/roslyn,jrharmon/roslyn,tmat/roslyn,nagyistoce/roslyn,khellang/roslyn,ericfe-ms/roslyn,chenxizhang/roslyn,jkotas/roslyn,basoundr/roslyn,paulvanbrenk/roslyn,Maxwe11/roslyn,MichalStrehovsky/roslyn,oocx/roslyn,sharadagrawal/Roslyn,yeaicc/roslyn,thomaslevesque/roslyn,taylorjonl/roslyn,jaredpar/roslyn,jeremymeng/roslyn,RipCurrent/roslyn,oberxon/roslyn,tsdl2013/roslyn,srivatsn/roslyn,BugraC/roslyn,taylorjonl/roslyn,supriyantomaftuh/roslyn,jaredpar/roslyn,EricArndt/roslyn,DustinCampbell/roslyn,HellBrick/roslyn,stephentoub/roslyn,AdamSpeight2008/roslyn-AdamSpeight2008,jasonmalinowski/roslyn,stebet/roslyn,ErikSchierboom/roslyn,jkotas/roslyn,khellang/roslyn,budcribar/roslyn,BugraC/roslyn,MattWindsor91/roslyn,YOTOV-LIMITED/roslyn,wvdd007/roslyn,natidea/roslyn