[7.2] Update the Config guide 'Transactions' chapter to link to the Troubleshooting Transactions guide

The Transactions guide reuses most of the topics in the Configuration guide 'Configuring Transactions' chapter [1]. This chapter needs to be updated to link to the transactions guide, similar to 'Configuring Webservices' chapter [2]. [1] https://access.qa.redhat.com/documentation/en-us/jboss_enterprise_application_platform_continuous_delivery/15/html-single/configuration_guide/#configuring_transactions [2] https://access.qa.redhat.com/documentation/en-us/jboss_enterprise_application_platform_continuous_delivery/15/html-single/configuration_guide/#configuring_web_services_subsystem