Not sure you can claim a "how-to" guide for good tooltip design in UI if you don't offer actual design guidelines or skip past the mobile view altogether? Especially since that's how more than 50% consume the web (not including apps) that don't offer hover states. I see you've covered the different types of tooltips with a few general pointers, but in my opinion, the guide is still missing. Also, in your examples, some don't follow accessibility guidelines for contrast, and a few have questionable padding/spacing. Maybe do some more research and then build out your article or change the title to something like "Common tooltip designs in UI"?