Update README.md

Signed-off-by: Allan Lei <[email protected]>

README.md

@@ -1 +1,35 @@
-# action-git-diff
+# action-git-diff
+
+## Usage
+
+## Inputs 📥
+
+| Input | Required? | Default | Description |
+| ----- | --------- | ------- | ----------- |
+| `head-ref` | no | `HEAD` | head ref to use for the git diff |
+| `base-ref` | no | `HEAD~1` | base ref to use for the git diff |
+| `default-branch` | no | `${{ github.ref_name }}` | Branch to use when `HEAD` is referenced |
+| `status` | no | `d` | Change status of the files to filter by. See https://git-scm.com/docs/git-diff#Documentation/git-diff.txt---diff-filterACDMRTUXB82308203  |
+| `filename-pattern` | no | `**/*` | Filename globs to filter by |
+| `token` | no | `.` | Github token to use |
+
+## Outputs 📤
+
+| Output | Description |
+| ------ | ----------- |
+| `filenames` | List of changed filenames in JSON format |
+| `json` | Raw data of the comparison in JSON |
+
+### Example
+
+#### Using the action for Pushes / PRs
+```
+    steps:
+    - name: Generate Changed Filenames
+      uses: swaglive/action-git-diff@main
+      with:
+        head-ref: ${{ github.event.pull_request.head.sha || github.event.after || 'HEAD' }}
+        base-ref: ${{ github.event.pull_request.base.sha || github.event.before || 'HEAD~1' }}
+        filename-pattern: |-
+          **/*.js
+```