Note: You should have a local copy of the image on your computer
You can insert the image in the Jupyter notebook itself. This way you don't need to keep the image separately in the folder.
Steps:
Convert the cell to markdown
by:
Now go to menu bar and select Edit -> Insert Image.
Select image from your disk and upload.
Press Ctrl+Enter or Shift+Enter.
This will make the image as part of the notebook and you don't need to upload in the directory or Github. I feel this looks more clean and not prone to broken URL issue.