fix(docs): Update macOS contributing info
fix(docs): Update macOS contributing info

Changelog-entry: Update docs
Change-type: patch
Signed-off-by: Robert Vojta <12e9293ec6b30c7fa8a0926af42807e929c1684f@balena.io>

resin-io/resin-etcher,resin-io/herostratus,resin-io/herostratus,resin-io/etcher,resin-io/etcher,resin-io/etcher,resin-io/etcher,resin-io/etcher,resin-io/resin-etcher