Move Style Guide to docs (#1781)
Move Style Guide to docs (#1781)

In line with our aim to bring all docs into one centralised location, I have moved the style guide to the main docs repo.
exercism/x-common,jmluy/x-common,petertseng/x-common,jmluy/x-common,exercism/x-common,jmluy/x-common,petertseng/x-common