Clarify use of `loading` property (#40488)
Clarify use of `loading` property (#40488)

I was a little confused by the `loading` property having the value `<header />`. I think that property is meant to show a loading state while the file is being loaded? If my assumption is correct, I think this change makes sense.
JeromeFitz/next.js,JeromeFitz/next.js,JeromeFitz/next.js,JeromeFitz/next.js