docs/install: Make Error Handling head consistent
docs/install: Make Error Handling head consistent

Closes https://github.com/coala-analyzer/coala/issues/2133

karansingh1559/coala,Asalle/coala,Asalle/coala,SanketDG/coala,jayvdb/coala,ManjiriBirajdar/coala,damngamerz/coala,sagark123/coala,Balaji2198/coala,meetmangukiya/coala,MariosPanag/coala,ManjiriBirajdar/coala,ManjiriBirajdar/coala,tushar-rishav/coala,coala-analyzer/coala,shreyans800755/coala,jayvdb/coala,sagark123/coala,arjunsinghy96/coala,Asnelchristian/coala,Balaji2198/coala,arush0311/coala,Balaji2198/coala,tushar-rishav/coala,coala-analyzer/coala,Asalle/coala,NiklasMM/coala,sils1297/coala,aptrishu/coala,coala/coala,abhiroyg/coala,JohnS-01/coala,aptrishu/coala,aptrishu/coala,yashtrivedi96/coala,kartikeys98/coala,refeed/coala,sagark123/coala,shreyans800755/coala,coala-analyzer/coala,Asnelchristian/coala,yashLadha/coala,ayushin78/coala,impmihai/coala,jayvdb/coala,MariosPanag/coala,vinc456/coala,damngamerz/coala,tushar-rishav/coala,stevemontana1980/coala,sils1297/coala,karansingh1559/coala,nemaniarjun/coala,arush0311/coala,ayushin78/coala,meetmangukiya/coala,impmihai/coala,nemaniarjun/coala,JohnS-01/coala,RJ722/coala,stevemontana1980/coala,arush0311/coala,CruiseDevice/coala,yashLadha/coala,vinc456/coala,yashtrivedi96/coala,netman92/coala,yashtrivedi96/coala,damngamerz/coala,sils1297/coala,stevemontana1980/coala,incorrectusername/coala,CruiseDevice/coala,RJ722/coala,mr-karan/coala,Shade5/coala,impmihai/coala,rimacone/testing2,refeed/coala,SanketDG/coala,incorrectusername/coala,CruiseDevice/coala,arjunsinghy96/coala,refeed/coala,incorrectusername/coala,netman92/coala,RJ722/coala,JohnS-01/coala,vinc456/coala,kartikeys98/coala,shreyans800755/coala,netman92/coala,mr-karan/coala,NiklasMM/coala,coala/coala,rimacone/testing2,arjunsinghy96/coala,Shade5/coala,SanketDG/coala,Shade5/coala,coala/coala,Nosferatul/coala,mr-karan/coala,abhiroyg/coala,Asnelchristian/coala,NiklasMM/coala,karansingh1559/coala,Nosferatul/coala,kartikeys98/coala,MariosPanag/coala,ayushin78/coala,nemaniarjun/coala,abhiroyg/coala,rimacone/testing2,Nosferatul/coala,yashLadha/coala,meetmangukiya/coala