readme, v4 stuff

.github/workflows/grit-check.yaml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: grit-check
         uses: ./
         with:

README.md

@@ -1,5 +1,55 @@
-# github-action-check
+# Grit GitHub Action
 
+This action runs the Grit CLI to report any violations of your configured [Grit patterns](https://docs.grit.io/guides/config).
+
+## Usage
+
+You can add it as a step in your GitHub Actions workflow to automatically check for violations on every push:
+
+```
+  - name: Grit
+    uses: getgrit/github-action-check@v0
+    with:
+      # Optional additional arguments to pass to the `grit check` command
+      args: ''
+```
+
+## Inputs
+
+### `args`
+Specify [additional arguments](https://docs.grit.io/cli/reference#grit-check) to pass to the `grit check` command.
+
+By default, only warning and error patterns are reported. To include info patterns, use `--level`.
+
+```
+  - name: Grit
+    uses: getgrit/github-action-check@v0
+    with:
+      args: '--level info'
+```
+
+## Example workflow
+
+```
+name: grit-check
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - '*'
+
+jobs:
+  run:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: grit-check
+        uses: getgrit/github-action-check@v0
+```
 
 ## License
 This action code is released under the [MIT License](LICENSE).