Clarify restore-keys description (#16922)

Co-authored-by: Vanessa <vgrl@github.com>

Author: lucascosti

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

@@ -102,7 +102,16 @@ For more information, see [`actions/cache`](https://github.com/actions/cache).
           ~/.gradle/wrapper
     ```
   - With `v1` of the `cache` action, only a single path is supported and it must be a directory. You cannot cache a single file.
-- `restore-keys`: **Optional** An ordered list of alternative keys to use for finding the cache if no cache hit occurred for `key`.
+- `restore-keys`: **Optional** A string containing alternative restore keys, with each restore key placed on a new line. If no cache hit occurred for `key`, these restore keys are used sequentially in the order provided to find and restore a cache. For example:
+
+  {% raw %}
+  ```yaml
+  restore-keys: |
+    npm-foobar-${{ hashFiles('package-lock.json') }}
+    npm-foobar-
+    npm-
+  ```
+  {% endraw %}
 
 ### Output parameters for the `cache` action