There are many ways to contribute to centsair, with the most common ones being contribution of code or documentation to the project. Improving the documentation is no less important than improving the code itself. If you find a typo in the documentation, or have made improvements, do not hesitate to send an email to support@centsair.lu or preferably submit a GitHub pull request.
But there are many other ways to help. In particular answering queries on the issue tracker, investigating bugs, and reviewing other developers' pull requests are very valuable contributions that decrease the burden on the projectmaintainers.
Another way to contribute is to report issues you're facing, and give a 👍 on issues that others reported and that are relevant to you. It also helps us if you spread the word: reference the project from your blog and articles, link to it from your website, or simply star it in GitHub to say "I use it".