docs: 📝 Improve doc for Docker image

#5

README.md

@@ -8,6 +8,21 @@ It's Free, Open-Source and self-hostable.
 - [Demo project using Fidbee](./demo/)
 - [Server example for webhooks](./server-example/)
 
+## Getting started
+
+See doc in [Fidbee React component](./lib/) directory.
+
+## Demo
+
+A Docker image is available on Docker Hub for a quick demo:
+
+```bash
+docker run -it --rm -p 8080:8080 --name fidbee octree/fidbee-demo
+```
+
+Then go to http://localhost:8080.
+Server's logs on new notifications are displayed in the container's logs.
+
 ## Contributing
 
 Please read [CONTRIBUTING.md](CONTRIBUTING.md) for details on our code of conduct, and the process for submitting pull requests to us.
@@ -20,4 +35,4 @@ See also the list of [contributors](https://github.com/octree-gva/fidbee/graphs/
 
 ## License
 
-This project is licensed under the AGPL v3 License - see the [LICENSE.md](LICENSE.md) file for details
+This project is licensed under the AGPL v3 License - see the [LICENSE.md](LICENSE.md) file for details