Changes usage rights placeholder text

This makes it so people don't think we have the
default copyright on their uploaded files.

closes CNVS-17266

Test Plan:
  - Enable Usage Rights
  - Go to New Files
  - Open a usage rights dialog
  - The copyright holder field should have
    '(c) 2001 Acme Inc.' as placeholder text

Change-Id: I87235206b7602a1e63a8d5d17a7f6bb5ee9fc9a6
Reviewed-on: https://gerrit.instructure.com/45342
Product-Review: Cosme Salazar <cosme@instructure.com>
Reviewed-by: Ryan Shaw <ryan@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>