Link image to full size image in markdown

This is the markup for adding image in Markdown:

![Alt text here](/images/foo.png)

To make clicking on image open a bigger version of the same image, do this:

[![Alt text here](/images/foo.png)](/images/foo-big.png)

I figured this out intuitively before finding out it’s right there in the docs and probably common knowledge to most Markdown users but I didn’t use it until recently.