Add documentation for actions/setup-node pnpm cache (#8389)

Author: jacobwgillespie

content/actions/guides/building-and-testing-nodejs.md

@@ -265,7 +265,27 @@ steps:
 - run: yarn test
 ```
 
-To cache dependencies, you must have a `package-lock.json` or `yarn.lock` file in the root of the repository. If you need more flexible customization, you can use the [`cache` action](https://github.com/marketplace/actions/cache). For more information, see "<a href="/actions/guides/caching-dependencies-to-speed-up-workflows" class="dotcom-only">Caching dependencies to speed up workflows</a>".
+The following example caches dependencies for pnpm (v6.10+).
+
+```yaml{:copy}
+{% data reusables.actions.actions-not-certified-by-github-comment %}
+
+# NOTE: pnpm caching support requires pnpm version >= 6.10.0
+
+steps:
+- uses: actions/checkout@v2
+- uses: pnpm/action-setup@646cdf48217256a3d0b80361c5a50727664284f2
+  with:
+    version: 6.10.0
+- uses: actions/setup-node@v2
+  with:
+    node-version: '14'
+    cache: 'pnpm'
+- run: pnpm install
+- run: pnpm test
+```
+
+To cache dependencies, you must have a `package-lock.json`, `yarn.lock`, or `pnpm-lock.yaml` file in the root of the repository. If you need more flexible customization, you can use the [`cache` action](https://github.com/marketplace/actions/cache). For more information, see "<a href="/actions/guides/caching-dependencies-to-speed-up-workflows" class="dotcom-only">Caching dependencies to speed up workflows</a>".
 
 ## Building and testing your code
 

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

@@ -26,7 +26,7 @@ To cache dependencies for a job, you'll need to use {% data variables.product.pr
 
 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). 
 
-To cache and restore dependencies for npm or Yarn, you can use the [`actions/setup-node` action](https://github.com/actions/setup-node).
+To cache and restore dependencies for npm, Yarn, or pnpm, you can use the [`actions/setup-node` action](https://github.com/actions/setup-node).
 
 {% warning %}