Update CONTRIBUTING.md
Update CONTRIBUTING.md

Updated CONTRIBUTING.MD to link to gwells license file.
rstens/gwells,rstens/gwells,rstens/gwells,rstens/gwells,SethGreylyn/gwells,bcgov/gwells,SethGreylyn/gwells,bcgov/gwells,bcgov/gwells,SethGreylyn/gwells,bcgov/gwells,SethGreylyn/gwells