Our own, Andrew “Tianon” Page, VP of Development for InfoSiftr, was one of the presenters at DockerCon last month. His talk covers many aspects of contributing to the Docker project. As he points out, not all of them involve submitting code improvements via pull requests, or even having sizable coding knowledge. Contributions can come in the form of technical help on IRC and the mailing lists, reviewing/triaging GitHub issues and pull requests, filing new issues, packaging, and of course sending pull requests for bug fixes, feature enhancements, and/or documentation.
Here is the link to his presentation: Contributing to Docker