I want to insert an image from a URL source in a Markdown code block in Jupyter Notebooks.
So far this is what I have:
 However, it doesn't include and image when I run the cell.
Both of these two instructions work for showing images in a Jupyter notebook markdown cell:
 or with HTML
<img src="https://scikit-learn.org/stable/_static/scikit-learn-logo-small.png" alt="image info" /> The image is shown when the markdown cell is executed (run).
I entered the code slightly differently from your code. I got the image to display when the markdown cell was run.
Below is the code used for displaying the .jpg in the Markdown cell. A photo of the output also follows below.
 Initial square bracket contains the name of image and in the bracket put your file path.
So your code should look like this. Make sure you are in Markdown mode:
