You can also contribute to Docker by other means beyond contributing to the Docker code or feature sets. You can help by using the knowledge you have obtained to help others in their support channels. The community is very open and someone is always willing to help. I have found it of great help when I run into something that I come across and am found scratching my head. It's also nice to get help but also to contribute back to others then; a nice give and take. It also is a great place to harvest ideas for you to use. You can see what questions others are asking based on their setups and it could spur ideas that you may want to think about using in your environment.

You can also follow the GitHub issues that are brought up about the services. These could be feature requests and how Docker may implement them or they could be issues that have cropped up through the usage of services. You can help test out the issues that others are experiencing to see whether you can replicate the issue or whether you find a possible solution to their issue.

Docker has a very active community which can be found at https://community.docker.com/; here you will not only be able to see the latest community news and events, you will also be able to chat with Docker users and developers in their Slack channels. At the time of writing, there are over 80 channels covering all sorts of topics such as Docker for Mac, Docker for Windows, Alpine Linux, Swarm, Storage, and Network to name but a few, with hundreds of active users at any one time.

Finally, there are also the Docker forums, which can be found at https://forums.docker.com/. These are a good source if you want to search for topics/problems or keywords.