Added note about why Next.js used 307 and 308 status codes

docs/api-reference/next.config.js/redirects.md

@@ -44,6 +44,9 @@ module.exports = {
 - `source` is the incoming request path pattern.
 - `destination` is the path you want to route to.
 - `permanent` `true` or `false` - if `true` will use the 308 status code which instructs clients/search engines to cache the redirect forever, if `false` will use the 307 status code which is temporary and is not cached.
+
+> **Why does Next.js use 307 and 308?** Traditionally a 302 was used for a temporary redirect, and a 301 for a permanent redirect, but many browsers changed the request method of the redirect, from a `POST` to a `GET` request, regardless of the method used by the origin. For example, a `POST` request to `/users` to create a new user, and while using a temporary 302, would change the request method to `GET`. Next.js uses the 307 temporary redirect, and 308 permanent redirect status codes, and will preserve the request methods used.
+
 - `basePath`: `false` or `undefined` - if false the basePath won't be included when matching, can be used for external rewrites only.
 - `locale`: `false` or `undefined` - whether the locale should not be included when matching.
 - `has` is an array of [has objects](#header-cookie-and-query-matching) with the `type`, `key` and `value` properties.