update readme

Author: orsinium

.github/workflows/main.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
       - name: Run DepHell
-        uses: dephell/dephell_action@smoke
+        uses: dephell/dephell_action@master
         with:
           dephell-env: main
           python-version: ${{ matrix.python-version }}

README.md

@@ -2,7 +2,33 @@
 
 An official [GitHub Action](https://help.github.com/en/actions) to run [DepHell](https://github.com/dephell/dephell) commands.
 
+Input variables:
+
+- `dephell-env` -- DepHell environment to run.
+- `python-version` -- Python version to use when creating venv.
+- `dephell-version` -- DepHell version to install. The latest version is installed by default.
+
+## Example
+
+DepHell config (`pyproject.toml`):
+
+```toml
+[tool.dephell.main]
+from = {format = "pip", path = "requirements.txt"}
+command = "pytest"
+```
+
+GitHub Actions workflow (`.github/workflows/main.yml`):
+
 ```yaml
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
 jobs:
   pytest:
     runs-on: ubuntu-latest
@@ -14,8 +40,13 @@ jobs:
         uses: actions/setup-python@v2
         with:
           python-version: ${{ matrix.python-version }}
+      - name: Checkout
+        uses: actions/checkout@v2
       - name: Run DepHell
-        uses: actions/dephell
+        uses: dephell/dephell_action@master
         with:
           dephell-env: pytest
+          python-version: ${{ matrix.python-version }}
 ```
+
+See [DepHell documentation](https://dephell.readthedocs.io/config.html) for details on configuring DepHell.