Prepare readme for v0.1 pre-release

Author: webbertakken

README.md

@@ -10,3 +10,67 @@ action from the
 [Unity Actions](https://github.com/webbertakken/unity-actions) 
 collection before running this action. This action also requires the [Activation](https://github.com/marketplace/actions/unity-activate) step.
 
+## Documentation
+
+See the 
+[Unity Actions](https://github.com/webbertakken/unity-actions)
+collection repository for workflow documentation and reference implementation.
+
+## Usage
+
+Create or edit the file called `.github/workflows/main.yml` and add a job to it.
+
+```yaml
+name: Build project
+on: [push]
+jobs:
+  buildForWebGL:
+    name: Build for WebGL 🕸
+    runs-on: ubuntu-latest
+    steps:
+```
+
+Configure the builder as follows:
+
+```yaml
+      # Configure builder
+      - name: Build project
+        id: buildStep
+        uses: webbertakken/[email protected] # WIP (only webgl for now)
+        env:
+          UNITY_LICENSE: ${{ secrets.UNITY_LICENSE }}
+  
+          # Optional: Path to your project, leave blank for "./"
+          UNITY_PROJECT_PATH: path/to/your/project
+
+          # Name for your build
+          BUILD_NAME: TestBuild
+
+          # Optional: Builds path, leave blank for "build"
+          BUILDS_PATH: build
+
+          # Target platform for your build
+          BUILD_TARGET: WebGL
+
+          # Optional: <StaticBuildClass.StaticMethod>, defaults to Builder.BuildProject
+          BUILD_COMMAND: ""
+```
+
+You use the id to **upload your built files** like so:
+
+```yaml
+      # Upload distributables
+      - name: Upload Build
+        uses: actions/upload-artifact@v1
+        with:
+          name: Build
+          path: ${{ steps.buildStep.outputs.allBuildsPath }}
+```
+
+Commit and push your workflow definition.
+
+## More actions
+
+Visit 
+[Unity Actions](https://github.com/webbertakken/unity-actions) 
+to find related actions for Unity.