Any GitHub wiki can be cloned by appending wiki.git to the repo url, so the clone url for
the repo https://myorg/myrepo/ is: git@github.com/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.
You need to clone the wiki repo and edit it on your system.
Add images to the images directory (or subdirectory below it). For example: images/project-architecture/project-architecture-overview.png.
In your wiki page markup, embed an image link in the following format:
[[/images/path/to/image.ext|ALT TEXT]]
(The leading / is so the path is still correct when editing a wiki page in subdirectory. You can't put pages in sub-directories when editing via the online editor, but you can when you work with clone repo.)
Commit and push your changes.
You need to clone the wiki repo and edit it on your system.
Add files to the files directory (or subdirectory below it). For example: files/project-presentation.pdf`.
In your wiki page markup, add the file link in the following format:
[link text](files/path/to/file "ALT TEXT")
For example:
[Project Presentation](files/project-presentation.pdf "Project Presentation PDF")
Commit and push your changes.