Update links for event listing classes

A reader in the Dev Guide pointed out links in the Service Builder chapter that are no longer working. This PR corrects these links so they function properly. The links and conversation are located [here](https://www.liferay.com/documentation/liferay-portal/6.2/development/-/ai/write-remote-service-classes-liferay-portal-6-2-dev-guide-04-en).