How do I clone a GitHub wiki?
Any GitHub wiki can be cloned by appending
wiki.git to the repo url, so the clone url for
firstname.lastname@example.org/myorg/myrepo.wiki.git (for ssh) or
https://github.com/my/myrepo.wiki.git (for https).
You make edits, and commit and push your changes, like any normal repo.
How do I add images to a wiki page?
You need to clone the wiki repo and edit it on your system.