docs: Fixes broken link on v4 auth0 provider page (#8998)

Update auth0.md

Author: pippinmole

docs/docs/providers/auth0.md

@@ -15,7 +15,7 @@ https://manage.auth0.com/dashboard
 
 The **Auth0 Provider** comes with a set of default options:
 
-- [Auth0 Provider options](https://github.com/nextauthjs/next-auth/blob/main/packages/next-auth/src/providers/auth0.ts)
+- [Auth0 Provider options](https://github.com/nextauthjs/next-auth/blob/v4/packages/next-auth/src/providers/auth0.ts)
 
 You can override any of the options to suit your own use case.