reference ruby/setup-ruby for cache (#2464)

Co-authored-by: Lucas Costi <lucascosti@users.noreply.github.com>

Author: Laura Gerhardt

content/actions/guides/caching-dependencies-to-speed-up-workflows.md

@@ -22,7 +22,7 @@ Workflow runs often reuse the same outputs or downloaded dependencies from one r
 
 Jobs on {% data variables.product.prodname_dotcom %}-hosted runners start in a clean virtual environment and must download dependencies each time, causing increased network utilization, longer runtime, and increased cost. To help speed up the time it takes to recreate these files, {% data variables.product.prodname_dotcom %} can cache dependencies you frequently use in workflows.
 
-To cache dependencies for a job, you'll need to use {% data variables.product.prodname_dotcom %}'s `cache` action. The action retrieves a cache identified by a unique key. For more information, see [`actions/cache`](https://github.com/actions/cache).
+To cache dependencies for a job, you'll need to use {% data variables.product.prodname_dotcom %}'s `cache` action. The action retrieves a cache identified by a unique key. For more information, see [`actions/cache`](https://github.com/actions/cache). If you are caching Ruby gems, instead consider using the Ruby maintained action, which can cache bundle installs on initiation. For more information, see [`ruby/setup-ruby`](https://github.com/ruby/setup-ruby#caching-bundle-install-automatically).
 
 {% warning %}