Possibility to split antora-playbook.yml in multiple files (i.e., extend playbook)

Currently, Antora can only take a single antora-playbook.yml file as input.

It would be useful to be able to provide multiple .yml files to Antora (who would do the YAML merge), as it would make it possible to reuse subsets of playbooks for different Antora-generated websites.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information