The documentation content is tracked in the Docs Repository. Different versions of the documentation are available, that match the major versions of PrestaShop.
Contributions to the content, such as adding a new page, updating or fixing some existing reference, must be submitted as a Pull Request against the right branch on the repository.
1.7.x branch.8.x branch.Consequently, if you want to update the 8.x documentation, you must submit your Pull Request against the 8.x branch.
If your contribution is applicable for multiple PrestaShop versions, we suggest submitting it against the highest version first, then backporting the changes into previous versions in independent Pull Requests.