I beg you, if you are a developer of an open source app or program - add screenshots of your app to the README file. When looking for the perfect app, I had to install dozens of them just to see what the user interface looked like and whether it suits me. This will allow users to decide if the app they choose will suit them… Please, don’t think about it, just do it…
Or, hell, just add a “screenshots” folder to the repo and mention its existence in the readme.
The best solution is to create an issue and attach the pictures there. You can then link in README and not bloat the repository.
If I clone the repo I expect everything to work, including the readme.
That’s a good point non-text shouldn’t be in the git tree, git-lfs is another solution for that though