[eslint config] [*] [docs] Specify yarn-specific install instructions

Attempts to clarify and address issue https://github.com/airbnb/javascript/issues/1508#issuecomment-319113807

Recommends yarn users to list peer dependencies and then install each peer dependency with specified version.

Prior yarn instructions led users to install the latest version of each peer dependency which, in some cases, led to errors if the latest version of a peer dependency did not have rules that this package uses.