How to upload an attachment to GitHub wiki? [closed]

I know how to reference it from wikis but where in GitHub site do I upload the attachment? Thanks a lot!

How do I attach a file to a GitHub issue?

To attach a file to an issue or pull request conversation, drag and drop it into the comment box. Alternatively, you can click the bar at the bottom of the comment box to browse, select, and add a file from your computer. Tip: In many browsers, you can copy-and-paste images directly into the box.

Just to answer it shortly: You can't. You have to upload your images somewhere else (like in a repository or on an image hoster) and link it

But I agree with @jstephenson