Documentation: Clarify repository install
Documentation: Clarify repository install

The 'Installing from Git' section was ambiguous around the repositories
it was referring to. Removed the -e flag from the base repository
install commands and added reference to the forked repository.

Closes https://github.com/coala/coala/issues/4265

coala-analyzer/coala,arjunsinghy96/coala,Balaji2198/coala,Nosferatul/coala,Balaji2198/coala,nemaniarjun/coala,shreyans800755/coala,nemaniarjun/coala,coala-analyzer/coala,arjunsinghy96/coala,shreyans800755/coala,Asnelchristian/coala,SanketDG/coala,karansingh1559/coala,RJ722/coala,karansingh1559/coala,rimacone/testing2,Nosferatul/coala,damngamerz/coala,coala/coala,Asnelchristian/coala,rimacone/testing2,jayvdb/coala,Balaji2198/coala,kartikeys98/coala,coala/coala,coala/coala,RJ722/coala,aptrishu/coala,Asnelchristian/coala,Asalle/coala,Asalle/coala,kartikeys98/coala,CruiseDevice/coala,shreyans800755/coala,CruiseDevice/coala,RJ722/coala,kartikeys98/coala,SanketDG/coala,jayvdb/coala,coala-analyzer/coala,Asalle/coala,damngamerz/coala,nemaniarjun/coala,jayvdb/coala,arjunsinghy96/coala,aptrishu/coala,MariosPanag/coala,CruiseDevice/coala,SanketDG/coala,karansingh1559/coala,damngamerz/coala,aptrishu/coala,Nosferatul/coala,MariosPanag/coala,MariosPanag/coala,rimacone/testing2