Update lib/linguist/languages.yml
Update lib/linguist/languages.yml

Add .gv (GraphViz) file extension to DOT language.
martynbm/linguist,sideci-sample/sideci-sample-linguist,pcantrell/linguist,c-lipka/linguist,MadcapJake/linguist,Mailaender/linguist,a0viedo/linguist,erkyrath/linguist,davidzchen/linguist,FStarLang/linguist,CoderXpert/linguist,SRI-CSL/linguist,MahmoudFayed/linguist,iblech/linguist,meunierfrederic/octocatlinguist,matt40k/linguist,jrnold/linguist,alvarotrigo/linguist,nburkley/linguist,yscho/linguist,alvarotrigo/linguist,jtbandes/linguist,ChaiScript/linguist,pchaigno/linguist,scttnlsn/linguist,mwpastore/linguist,FStarLang/linguist,yyx990803/linguist,sebgod/linguist,georgesuperman/linguist,mattn/linguist,blakeembrey/linguist,MostAwesomeDude/linguist,manveru/linguist,assimovt/ling-ist,christop/linguist,whitj00/linguist,ammaraskar/linguist,steventhanna/linguist,mattn/linguist,anhongyue/test222,github/linguist,sideci-sample/sideci-sample-linguist,yscho/linguist,manveru/linguist,R4PaSs/linguist,pcantrell/linguist,thejameskyle/linguist,marcojonker/test,thejameskyle/linguist,scttnlsn/linguist,hcutler/linguist,jtbandes/linguist,ya7lelkom/linguist,steventhanna/linguist,ya7lelkom/linguist,jjatria/linguist,JJ/linguist,wcandillon/linguist,chiranjeevjain/linguist,douglas-larocca/linguist,yyx990803/linguist,chiranjeevjain/linguist,whitj00/linguist,alitalia/linguist,meunierfrederic/octocatlinguist,stanhu/linguist,igat259/linguist,ppaulweber/github-linguist,iblech/linguist,CoderXpert/linguist,christop/linguist,phpsgi/linguist,0a-/linguist,erkyrath/linguist,anhongyue/test222,PsichiX/linguist,mcandre/linguist,gitlabhq/linguist,phpsgi/linguist,R4PaSs/linguist,kr/linguist,maxogden/linguist,Rockyspade/linguist,PsichiX/linguist,github/linguist,c-lipka/linguist,meunierfrederic/octocatlinguist,cokeboL/linguist,georgesuperman/linguist,ilyes14/linguist,MadcapJake/linguist,JJ/linguist,yyx990803/linguist,JJ/linguist,ilyes14/linguist,assimovt/ling-ist,pchaigno/linguist,kyoungrok0517/linguist,cokeboL/linguist,tschf/linguist,MostAwesomeDude/linguist,github/linguist,blakeembrey/linguist,ammaraskar/linguist,marcojonker/test,Ocramius/linguist,hcatlin/linguist,matt40k/linguist,stanhu/linguist,seanders/linguist,erkyrath/linguist,hcatlin/linguist,stanhu/linguist,sagar290/linguist,sebgod/linguist,osorgin/linguist,adamkaplan/linguist,BerkeleyTrue/linguist,mcandre/linguist,tschf/linguist,bluebear94/linguist,nburkley/linguist,alitalia/linguist,BerkeleyTrue/linguist,cybernet14/linguist,jjatria/linguist,JJ/linguist,CegepVictoriaville/linguist,ppaulweber/github-linguist,cybernet14/linguist,davidzchen/linguist,wcandillon/linguist,MahmoudFayed/linguist,sagar290/linguist,sebgod/linguist,Mx7f/linguist,kyoungrok0517/linguist,bluebear94/linguist,seanders/linguist,kr/linguist,yyx990803/linguist,adamkaplan/linguist,github/linguist,martynbm/linguist,douglas-larocca/linguist,osorgin/linguist,erkyrath/linguist,CegepVictoriaville/linguist,Mx7f/linguist,pchaigno/linguist,hcutler/linguist,sebgod/linguist,jrnold/linguist,a0viedo/linguist,Rockyspade/linguist,pchaigno/linguist,0a-/linguist,stanhu/linguist,SRI-CSL/linguist,mwpastore/linguist