Add pnpm caching support

README.md

@@ -7,7 +7,7 @@
 This action provides the following functionality for GitHub Actions users:
 
 - Optionally downloading and caching distribution of the requested Node.js version, and adding it to the PATH
-- Optionally caching npm/yarn dependencies
+- Optionally caching npm/pnpm/yarn dependencies
 - Registering problem matchers for error output
 - Configuring authentication for GPR or npm
 
@@ -41,7 +41,7 @@ nvm lts syntax: `lts/erbium`, `lts/fermium`, `lts/*`
 
 ### Caching packages dependencies
 
-The action has a built-in functionality for caching and restoring npm/yarn dependencies. Supported package managers are `npm`, `yarn`. The `cache` input is optional, and caching is turned off by default.
+The action has a built-in functionality for caching and restoring npm/yarn dependencies. Supported package managers are `npm`, `pnpm`, `yarn`. The `cache` input is optional, and caching is turned off by default.
 
 **Caching npm dependencies:**
 ```yaml
@@ -55,6 +55,21 @@ steps:
 - run: npm test
 ```
 
+**Caching pnpm dependencies:**
+```yaml
+steps:
+- uses: actions/checkout@v2
+- uses: pnpm/action-setup@v2
+  with:
+    version: 6.9.0
+- uses: actions/setup-node@v2
+  with:
+    node-version: '14'
+    cache: 'pnpm'
+- run: pnpm install
+- run: pnpm test
+```
+
 **Caching yarn dependencies:**
 ```yaml
 steps: