[INTERNAL] sap.m.MultiInput: Update addValidator documentation
[INTERNAL] sap.m.MultiInput: Update addValidator documentation

JIRA: BGSOFUIRILA-2675
Change-Id: Idee63f7ca39d64ce7923936186c908c09d1d3d90

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