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

- Corrections and additions to the documentation.
- Lifecycle methods are now @protected and documented

Change-Id: I57eb918da552890b383983f99b0314fbc98f21b8
JIRA: BGSOFUIRILA-2368

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