As of ansible-core 2.15.3, upstream moved documentation and examples to a separate dedicated repository (see the related changelogs).
This means that, starting from version 2.15.3 the ansible-core package will stop shipping documentation and a default configuration example under /etc/ansible/ansible.cfg.
Regarding the documentation, it is available online: https://docs.ansible.com/
As for the configuration file, as explained in the wiki, a base config can be generated with the following command:
ansible-config init --disabled > ansible.cfg
After updating from ansible-core <= 2.15.2-1 to >= 2.15.3-1, everyone using a custom global Ansible configuration file stored under /etc/ansible/ansible.cfg will have their configuration saved as a pacsave file.
To restore it, run the following command:
mv /etc/ansible/ansible.cfg.pacsave /etc/ansible/ansible.cfg