Docs: Add ref to ra-acl

[andrico1234]

I open sourced a utility module, ra-acl, to expand on the work done in ra-auth-acl, by adding a useAcl hook, as well as a handful of declarative components to abstract out the permission logic and keep the code clean

Even though this module was added to GitHub recently, I've been using it internally for a month on a production RA application

[fzaninotto]

Thanks!