Update CONTRIBUTING.md
Update CONTRIBUTING.md

Add a quick note, based on https://github.com/hotosm/learnosm/issues/225 's conversation - the quickest way to propose minor changes is via the online editing tools; running the full site or translations are more advanced topics.
hotosm/learnosm,feyeandal/test,Anwaario/Nick-Tallguy.github.io,furaidochikin/learnosm,jmarlena/learnosm,jmarlena/learnosm-ux-staging-site,Nick-Tallguy/Nick-Tallguy.github.io,Anwaario/Nick-Tallguy.github.io,althio/learnosm,Nick-Tallguy/Nick-Tallguy.github.io,hotosm/learnosm,Anwaario/Nick-Tallguy.github.io,hotosm/learnosm,jmarlena/learnosm-ux-staging-site,Nick-Tallguy/Nick-Tallguy.github.io,jmarlena/learnosm-ux-staging-site,althio/learnosm,althio/learnosm,furaidochikin/learnosm,jmarlena/learnosm,feyeandal/test,Anwaario/Nick-Tallguy.github.io,Nick-Tallguy/Nick-Tallguy.github.io,furaidochikin/learnosm,jmarlena/learnosm,althio/learnosm,feyeandal/test,feyeandal/test,Nick-Tallguy/Nick-Tallguy.github.io,jmarlena/learnosm,jmarlena/learnosm-ux-staging-site,hotosm/learnosm,furaidochikin/learnosm