Documentation & Examples
Documentation for open source projects can be found below.
SingularityCE
Example containers for common applications can be found in the Sylabs Cloud Library, built from the definition files at github.com/sylabs/examples.
The Singularity Community Catalog is also a great resource to find definition files that have been shared in GitHub repositories.
You can contribute to the user guide at github.com/sylabs/singularity-userdocs, and the admin guide at github.com/sylabs/singularity-admindocs.