Update image styling doc (#28724)
Update image styling doc (#28724)

In talking to partners, I've seen a lot of confusion about the number of wrapping `<div>`s around the image element rendered by `next/image`. There's always just one single wrapper--this PR updates the docs to make that a little more explicit.

flybayer/next.js,azukaru/next.js,JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js,azukaru/next.js,zeit/next.js,JeromeFitz/next.js,flybayer/next.js,zeit/next.js,flybayer/next.js,zeit/next.js,flybayer/next.js