docs(readme): update README.md about new action arguments

README.md

@@ -6,21 +6,34 @@ This action generates a changelog based on your Git history using [git-cliff](ht
 
 ### Inputs
 
-* `config`: Path of the configuration file. Default: `"cliff.toml"`
-* `args`: Arguments to pass to git-cliff. Default: `"-v"`
+- `config`: Path of the configuration file. Default: `"cliff.toml"`
+- `args`: Arguments to pass to git-cliff. Default: `"-v"`
 
 ### Outputs
 
-* `changelog`: The generated changelog.
+- `changelog`: Output file that contains the generated changelog.
+
+### Environment
+
+- `OUTPUT`: Output file. Default: `"git-cliff/CHANGELOG.md"`
 
 ### Examples
 
-```
-- name: Changelog Generator
+```yml
+- name: Checkout
+  uses: actions/checkout@v2
+  with:
+    fetch-depth: 0
+- name: Generate a changelog
   uses: orhun/git-cliff-action@v1
+  id: git-cliff
   with:
     config: cliff.toml
     args: --verbose
+  env:
+    OUTPUT: CHANGELOG.md
+- name: Print the changelog
+  run: cat "${{ steps.git-cliff.outputs.changelog }}"
 ```
 
 ## Credits