ENYO-3833: Update Repeater documentation

Issue
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The `enyo.Repeater` documentation had become updated, incorrectly stating that the `build` method is always called when `setCount` is called, even if the count remains the same.

Fix
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Update the documentation to demonstrate the setter pattern and include the use of the `force` parameter.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>