ConfigurationGathering: Fix typo in docstring
ConfigurationGathering: Fix typo in docstring

This changes Alernative to Alternative.

Closes https://github.com/coala/coala/issues/4518

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