docs(buttons): add documentation on `uncheckable`
docs(buttons): add documentation on `uncheckable`

- Add documentation on the `uncheckable` attribute

Closes #4102
Closes #4123

deeg/bootstrap,carlosjunior/bootstrap,GirishKumrawat/bootstrap,pireerliu/bootstrap,filso/bootstrap,drocbuster/My_AngularJS_Repo,elancom/bootstrap-1,burlhock/bootstrap,SimilarWeb/bootstrap,dabos-GFI/angular-ui-bootstrap,nicklv/bootstrap,buchslava/bootstrap,leyanlo/bootstrap,pmalikbtech/bootstrap,RobJacobs/bootstrap,jordangraft/bootstrap,shadowdaw/bootstrap,mabi/bootstrap,WXwangxin/bootstrap,dmc2015/bootstrap,shihang0001/bootstrap,SystemDisc/bootstrap,codedogfish/angular-ui-bootstrap,karelcallens/bootstrap,shiftagent/ui-bootstrap,shootermv/bootstrap,folsom-labs/bootstrap,stereocilia/bootstrap,Xephi/bootstrap,daviesgeek/bootstrap,fernando-sendMail/bootstrap,zhaokunfay/bootstrap,suryasingh/bootstrap,elancom/bootstrap-1,hyoda/bootstrap,vfiles/bootstrap,JonathanGawrych/bootstrap,rgolea/bootstrap,gfaceless/bootstrap,ksheedlo/bootstrap,mykhaylo-/bootstrap,voyagecontrol/bootstrap,jaydiablo/bootstrap,Bugagazavr/bootstrap,kmccaw/bootstrap,jaydiablo/bootstrap,Crunch-io/bootstrap,2363140194/bootstrap,krossoverintelligence/bootstrap,universsky/bootstrap-1,SystemDisc/bootstrap,vfiles/bootstrap,christor/bootstrap,infowrap/bootstrap,thomassorensen/bootstrap,filso/bootstrap,ehteshamkafeel/bootstrap,carlosjunior/bootstrap,birdy-/bootstrap,liiza/bootstrap,cdrewery/bootstrap,Gailby/bootstrap,miiihi/bootstrap,tmcgee123/bootstrap,JDeuker/bootstrap,xzoth/bootstrap,ChinnasamyM/bootstrap,rgolea/bootstrap,fjg1989/bootstrap,292388900/bootstrap,realityking/ui-bootstrap,fpipita/bootstrap,connyay/bootstrap,JonFerrera/ui-bootstrap,krossoverintelligence/bootstrap,shihang0001/bootstrap,teng2015/bootstrap,Bugagazavr/bootstrap,ChinnasamyM/bootstrap,angular-ui/bootstrap,themifycloud/bootstrap,birdy-/bootstrap,Schibum/bootstrap,Lincoln-xzc/angular-ui-bootstrap,linuxb/bootstrap,Servoy/bootstrap,fpipita/bootstrap,davereed/bootstrap,MikhailNazarov/bootstrap,inoxis91/bootstrap,connyay/bootstrap,stanzi83/bootstrap,Farael49/bootstrap,kongx73/bootstrap,BookingBug/bootstrap,obivandamme/bootstrap,madhudskumar/bootstrap,yubin-huang/bootstrap,ahsanbagwan/bootstrap,folsom-labs/bootstrap,alokpradhan/bootstrap,Foxandxss/bootstrap,guaido79/bootstrap,fabg21/bootstrap,gfaceless/bootstrap,yubin-huang/bootstrap,imskojs/bootstrap,MetSystem/bootstrap,franzherzog/bootstrap,wuhoujun/bootstrap,shadowdaw/bootstrap,Gailby/bootstrap,qpitlove/bootstrap,gato-gordo/bootstrap,JonathanGawrych/bootstrap,SandeepSikhakolli/bootstrap,oliversalzburg/bootstrap,spadgett/bootstrap,DenisCloutier/bootstrap,Farael49/bootstrap,ksheedlo/bootstrap,pireerliu/bootstrap,elijah513/bootstrap,yonglehou/bootstrap-1,freejavaster/bootstrap,inukshuk/bootstrap,SatvikPurohit/bootstrap,cgat/bootstrap,RobJacobs/bootstrap,iamcbh/bootstrap,gbasto/bootstrap,stanzi83/bootstrap,yjukaku/bootstrap,DiHuang1986/bootstrap,vsternbach/bootstrap,ahsanbagwan/bootstrap,mufl1h/bootstrap,josheche/bootstrap-1,nathan-j-brenner/bootstrap-1,kmccaw/bootstrap,mykhaylo-/bootstrap,zepheiryan/bootstrap,kemapak/bootstrap,KingMario/bootstrap-1,tobigun/bootstrap,deeg/bootstrap,wuwei111467/bootstrap,SandeepSikhakolli/bootstrap,azahreba/bootstrap,guaido79/bootstrap,yukisan/bootstrap,looker/bootstrap,alokpradhan/bootstrap,rhamid/bootstrap-1,gorork/bootstrap,shiftagent/ui-bootstrap,zhaokunfay/bootstrap,leyanlo/bootstrap,kirning/bootstrap-1,jackRogers/bootstrap,nobitagit/bootstrap,Emobe/bootstrap,mikesavior/bootstrap,Lincoln-xzc/angular-ui-bootstrap,Kpler/bootstrap,realityking/ui-bootstrap,suryasingh/bootstrap,pkdevbox/angular-ui-bootstrap,minzen/bootstrap,liiza/bootstrap,oliversalzburg/bootstrap,thalen/bootstrap,benhalverson/bootstrap,jackRogers/bootstrap,nicklv/bootstrap,linuxb/bootstrap,yjukaku/bootstrap,Xephi/bootstrap,pkdevbox/angular-ui-bootstrap,Kpler/bootstrap,xzoth/bootstrap,stereocilia/bootstrap,Anirudhk94/bootstrap,rasulnz/bootstrap,eftakharali/bootstrap,dabos-GFI/angular-ui-bootstrap,JonFerrera/ui-bootstrap,dsisejkovic/bootstrap,fjg1989/bootstrap,iamcbh/bootstrap,icfantv/bootstrap,benhalverson/bootstrap,daviesgeek/bootstrap,maoli1110/bootstrap,drocbuster/My_AngularJS_Repo,looker/bootstrap,kongx73/bootstrap,qpitlove/bootstrap,andrepitombeira/bootstrap,mikesavior/bootstrap,andrepitombeira/bootstrap,Nekle/bootstrap,edivancamargo/bootstrap,tmcgee123/bootstrap,SatvikPurohit/bootstrap,davious/angular-ui-bootstrap,DiHuang1986/bootstrap,codedogfish/angular-ui-bootstrap,justin-john/bootstrap-1,pkdevbox/bootstrap-1,angular-ui/bootstrap,eduncan26/bootstrap,rajesh-frontendengineer/bootstrap-1,cesarmarinhorj/AngularJS-bootstrap,2363140194/bootstrap,nlwillia/bootstrap,pkdevbox/bootstrap-1,sullivanpt/bootstrap,fmccown/bootstrap,MetSystem/bootstrap,benhalverson/bootstrap,ehteshamkafeel/bootstrap,linuxvom/bootstrap,pmalikbtech/bootstrap,maoli1110/bootstrap,wuwei111467/bootstrap,rasulnz/bootstrap,reiniergs/bootstrap,jordangraft/bootstrap,icfantv/bootstrap,wesleycho/bootstrap,matteopic/bootstrap,pdsoftplan/bootstrap,christor/bootstrap,dsisejkovic/bootstrap,fabg21/bootstrap,thalen/bootstrap,azahreba/bootstrap,burlhock/bootstrap,atulc007/bootstr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