[INTERNAL] sap.ui.core.EventBus: Add additional documentation
[INTERNAL] sap.ui.core.EventBus: Add additional documentation

Change-Id: I73e17ece9c3b14e724d66f0cc330dfbafa51a407
demo-kit-feedback: #1202

SAP/openui5,SAP/openui5,SAP/openui5,SAP/openui5