Cereal has been deprecated and is no longer needed by Stockpile. If you are interested in maintaining/updating it, feel free to open a GitHub issue.
You'll only need Cereal if a mod depends on it. It doesn't have any of its own functionality! If you experience a lot of crashes related to Cereal, feel free to submit an issue in the Issues tab above.
If you want to do any developing with Cereal (either for your own mod or for Cereal itself) or just want to see an example, then the GitHub repository is a good place to start! Any types of contributions-- bugfixes, performance improvements, documentation entries, desired features, etc.-- are welcome.