Newcomers_Guide.rst: Link style guidelines
Newcomers_Guide.rst: Link style guidelines

Adds instructions about code documentation and styling.
Links Writing_Documentation.rst and PEP8 guidelines for references.

Fixes https://github.com/coala/coala/issues/4255

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