You can open feature requests or bug reports as issues. Please check if there is a relevant existing issue before opening a new one, and include as much detail as you can in your issue.
If you can improve the documentation, feel free to submit a pull request or add to the project Wiki.
Feel free to submit pull requests for fixes or enhancements.
The generator code is a Gradle build script, so you will need Java installed. In addition, ImageMagick is required to generate the images.
The Gradle logic is written in Groovy, so you may want to refer to that documentation as well.
I recommend using IntelliJ IDEA as IDE since it seems to have the best support for Gradle and Groovy, however I sometimes use VS Code too.