[INTERNAL] sap.m.ComboBox: Documentation update
[INTERNAL] sap.m.ComboBox: Documentation update

All methods are now documented with their purpose,
parameters, return value and visibility.

JIRA: BGSOFUIRILA-2368
Change-Id: I0b6303d9c8ba66e218f5caab275d2408f5b3abf4

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