improve general documentation

src/redirect.rs

@@ -16,6 +16,11 @@ use Url;
 ///
 /// The default value will catch redirect loops, and has a maximum of 10
 /// redirects it will follow in a chain before returning an error.
+///
+/// - `limited` can be used have the same as the default behavior, but adjust
+///   the allowed maximum redirect hops in a chain.
+/// - `none` can be used to disable all redirect behavior.
+/// - `custom` can be used to create a customized policy.
 #[derive(Debug)]
 pub struct RedirectPolicy {
     inner: Policy,