[x] What is the purpose of the (specific) requirements file?
[x] Why are the versions not pinned? -> The requirements files are not actively used in the actual images, but provide repository-specific infrastructure around the images. Thus, pinning requirements to specific versions is not required.
Include comments in the requirements files (see https://stackoverflow.com/questions/9159757/can-i-add-comments-to-a-pip-requirements-file):