Newcomers_Guide.rst: Fix broken links
Newcomers_Guide.rst: Fix broken links

Change links from `coala.readthedocs.io` to `api.coala.io`
Fixes https://github.com/coala/coala/issues/3179

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