fix: update oauth2 java library link (#2228)

Author: YassineHaouzane

docs/hydra/guides/using-oauth2.mdx

@@ -12,7 +12,7 @@ Use open source & battle-tested libraries to consume OAuth2 and OpenID Connect:
   - [simple-oauth2](https://github.com/lelylan/simple-oauth2)
 - [Golang](https://github.com/golang/oauth2)
 - [PHP](https://github.com/thephpleague/oauth2-client)
-- [Java](https://spring.io/projects/spring-security-oauth)
+- [Java](https://spring.io/projects/spring-security)
 - [Objective C](https://github.com/openid/AppAuth-iOS)
 - [Erlang](https://github.com/exograd/erl-oauth2c)
 - [Elixir](https://github.com/scrogson/oauth2)