Improve unstable API badges

Unstable APIs currently get a badge highlighting the fact that they are unstable. However, it's hard to tell what exactly is being referenced given its size and where it appears.

This badge should appear on the same line as the api that is unstable (`flex flex-row gap-3 items-center`) and the label itself should be slightly adjusted (`px-2 py-1.5 text-base`) so it's size is more appropriate as a label for the adjacent text.