At this time a KB article is not able to be added to any kind of Favorites area within the tool. You can of course bookmark them within a browser's Favorites, but the tool does not have such a feature.
This has been a feature that client have expressed interest in. If you'd like to add your input to that feature for Product Management's benefit you can either submit this as a product idea via our Home page or let me know and I can create that enhancement ticket for you.
Please let me know if I can do anything else for you.