Listing all names right there in the notice is not scalable if there are many contributors, but the CC-BY-* 4.0 license seems fairly flexible on the details of “reasonable attribution”. The license requires the following elements to be preserved if they are present:
i. identification of the creator(s) of the Licensed Material and any others designated to receive attribution, in any reasonable manner requested by the Licensor (including by pseudonym if designated);
ii. a copyright notice;
iii. a notice that refers to this Public License;
iv. a notice that refers to the disclaimer of warranties;
v a URI or hyperlink to the Licensed Material to the extent reasonably practicable;
Additionally, other people must “indicate the Licensed Material is licensed under this Public License, and include the text of, or the URI or hyperlink to, this Public License.”
These requirements can be met “in any reasonable manner based on the medium”, in particular using URLs or hyperlinks.
Given that you are creating a LaTeX document and have (a) ample space and (b) the ability to place hyperlinks, I would suggest the following:
- Have a short and easily copyable attribution notice that identifies the original author, and other contributors as a group.
- Have an acknowledgements appendix in the document where contributors can add their name, if they wish so. Note that the CC-Attribution concept does not require all authors to be attributed, it only requires notices to be preserved if they exist.
For example, a short notice might look like the following, with links indicated in Markdown syntax:
The Example Book <https://github.com/example/book>
by [Original Author and the Example Contributors]
is licensed under a [Creative Commons Attribution-ShareAlike 4.0 International license].
: internal hyperlink to the appendix with acknowledgements
I would also include this notice in the README file, with the link to the acknowledgements adjusted accordingly. Adding a license file just so that GitHub autodetects the license is probably not useful.
The acknowledgements appendix would then provide space for everyone to list their name, possibly as a copyright notice if they want to.
The following people have contributed to the Example Book:
- Copyright 2021-2022 Original Author
- [Some Contributor](https://github.com/octocat)
- Copyright 2022 Random Contributor
- (and possibly others)
Now here's a great tip for running open source projects: you're not required to accept contributions. If a potential contributor decides to be difficult and has highly unusual attribution desires that are difficult to accommodate, you don't have to merge their contributions. How you run your project is not bound by the license you grant others.
To directly answer your questions:
Should you add notices anywhere?
I'd say yes. This makes the licensing status clear. If you don't add such notices, others are not required to preserve them. A good notice that also links to the license is helpful to others because their copies will be license-compliant by default.
Can you just add contributors to the notices?
Yes, definitely. But if you have more than two or so, this might not be scalable and I'd move to a separate appendix with acknowledgements, as outlined above. I'd probably defer this until the first contribution, though. Attributing large-scale contributions directly in the notice still seems sensible, e.g. if someone serves as an editor for a new edition.
Can you add separate notices for future contributions?
The CC-BY-* license does not impose a specific form, so you could do that – a single notice will be way less confusing, though. Adding multiple copyright notices is perfectly fine, though. A typical CC attribution line does not have the structure of a classic coyright notice, so I'd keep them distinct. Both CC-BY-* and GPL expect copyright notices to be preserved if they exist, but unlike CC, the GPl actively encourages adding copyright notices in its notice template.