Mention HTTP 303 See Other in redirects section (#35997)
Migrating from express to nextjs API routes broke one of our APIs because of how `redirect` works in nextjs vs. how it works in express. We need to redirect the user to a confirmation page via GET after making a POST request, which is not possible with `redirect`.
HTTP 303 seems to be the way to go in that case and I think it should be mentioned here.
## Documentation / Examples
- [ ] Make sure the linting passes by running `yarn lint`
