docs(contributing): Use RFC 2119 for template'specification
docs(contributing): Use RFC 2119 for template'specification

A specification SHOULD follow the RFC 2119

related to #30

base16-builder/base16-builder,aloisdg/base16-builder,aloisdg/base16-builder,aloisdg/base16-builder,base16-builder/base16-builder,base16-builder/base16-builder