ENYO-3833: Update Repeater documentation

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>
Updated wording to be clearer and more descriptive of when this call would be useful.
Merge pull request #663 from enyojs/ENYO-3833-aarontam

ENYO-3833: Update Repeater documentation

Reviewed-By: Ben Combee (ben.combee@lge.com)