[INTERNAL] sap.m.OverflowToolbar: Documentation improved
[INTERNAL] sap.m.OverflowToolbar: Documentation improved

Clarified which controls may overflow and mentioned the sap.m.IOverflowToolbarContent
interface in the control description.

Change-Id: I59f500c57c104349e479e0534742e12c51f3d0c0

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