Change npm dependencies install example

doc/ci/caching/index.md

@@ -206,10 +206,15 @@ templates](https://gitlab.com/gitlab-org/gitlab-foss/tree/master/lib/gitlab/ci/t
 
 ### Caching Node.js dependencies
 
-Assuming your project is using [npm](https://www.npmjs.com/) or
-[Yarn](https://classic.yarnpkg.com/en/) to install the Node.js dependencies, the
-following example defines `cache` globally so that all jobs inherit it.
-Node.js modules are installed in `node_modules/` and are cached per-branch:
+Assuming your project is using [npm](https://www.npmjs.com/)
+to install the Node.js dependencies.
+
+TIP: **Tip:**
+By default, npm stores cache data in the home folder `~/.npm`
+but [you can't cache things outside of the project directory](../yaml/README.md#cachepaths) so we simply tell npm to use `./.npm` instead.
+
+The following example defines `cache` globally so that all jobs inherit it.
+The npm cache is defined under `.npm/` and is cached per-branch:
 
 ```yaml
 #
@@ -221,10 +226,10 @@ image: node:latest
 cache:
   key: ${CI_COMMIT_REF_SLUG}
   paths:
-  - node_modules/
+  - .npm/
 
 before_script:
-  - npm install
+  - npm ci --cache .npm --prefer-offline
 
 test_async:
   script: