github добавляет изображения в readme
![alt text](http://url/to/img.png)
Cheerful Cheetah
![alt text](http://url/to/img.png)
You can also use relative paths like
![Alt text](relative/path/to/img.jpg?raw=true "Title")
Also try the following with the desired .fileExtention:
![plot](./directory_1/directory_2/.../directory_n/plot.png)
![alt text](http://url/to/img.png)
Try this markdown:
![alt text](http://url/to/img.png)
I think you can link directly to the raw version of an image if it's stored in your repository. i.e.
![alt text](https://github.com/[username]/[reponame]/blob/[branch]/image.jpg?raw=true)