README: Add usage information

README.md

@@ -2,6 +2,37 @@
 
 GitHub Action for reviewing package control schema.
 
+## Usage
+
+Add the following to Github Action workflow file.
+
+```yml
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: 3.11
+
+      - name: Run scheme tests
+        uses: packagecontrol/st-schema-reviewer-action@v1
+        with:
+          channel: channel.json
+          repository: repository.json
+          test_repositories: true
+```
+
+| Argument          | required | description
+|-------------------|:--------:|------------
+| channel           | no       | relative path to channel.json to verify schema for
+| repository        | no       | relative path to repository.json to verify schema for
+| test_repositories | no       | If `true` all remote repositories, listed in given channel are verified as well.
+
+
 ## Action releases
 
 It's recommended to create releases using semantically versioned tags – for example, v1.1.3 – and keeping major (v1) and minor (v1.1) tags current to the latest appropriate commit.