You start by creating a public repository with the same name as your GitHub username. In my case, I create a repository called "DaveBitter". In that repository, you add a
README.md. That's it. From here on you can use MarkDown to tell more about yourself, highlight skills, share social media links and anything you can think of. The README will now be used to display this content on your GitHub profile.
My GitHub profile README
As you can see, my README is fairly brief, but it does allow me to tell a bit more about myself, share a link to my articles and plug some social media channels. As always, some developers take full advantage and push for the limit. A collection with several of these examples can be found in this collection repository.
The biggest reason I like this feature is how it converts a "dry" profile page into a more human and personal page. Looking at some of the above-linked examples makes me reminiscent of pages on an old and retired Dutch social media platform called Hyves.
That's all. Make sure to add one of these README files to make the web more personalized, fun and awesome!