The -c flag stands for "entry-comments." It allows you to add a one-line comment to each file as it is added to the archive.
How to download source in ZIP format from GitHub? [duplicate]
If you are trying to download source code (often written in ) from a repository, you are looking for the platform-wide "Download ZIP" button.
Navigate to the main page of the repository, click the green <> Code button, and select Download ZIP from the dropdown menu.
A popular addition to zlib that adds the ability to create and extract .zip archives specifically.
You might be looking for documentation on the -c flag used in the standard zip command-line utility.