[11.x] restore string backed enum type (#10162)

Author: nshiro

routing.md

@@ -628,7 +628,7 @@ Typically, a 404 HTTP response will be generated if an implicitly bound model is
 <a name="implicit-enum-binding"></a>
 ### Implicit Enum Binding
 
-PHP 8.1 introduced support for [Enums](https://www.php.net/manual/en/language.enumerations.backed.php). To complement this feature, Laravel allows you to type-hint a [backed Enum](https://www.php.net/manual/en/language.enumerations.backed.php) on your route definition and Laravel will only invoke the route if that route segment corresponds to a valid Enum value. Otherwise, a 404 HTTP response will be returned automatically. For example, given the following Enum:
+PHP 8.1 introduced support for [Enums](https://www.php.net/manual/en/language.enumerations.backed.php). To complement this feature, Laravel allows you to type-hint a [string-backed Enum](https://www.php.net/manual/en/language.enumerations.backed.php) on your route definition and Laravel will only invoke the route if that route segment corresponds to a valid Enum value. Otherwise, a 404 HTTP response will be returned automatically. For example, given the following Enum:
 
 ```php
 <?php