qqq docs for installer mysql warning

The previous commit I68e79a8efe7cd625c12b5993074de9c3479e760b added a new
i18n string without a matching qqq, this rectifys that situation.

Bug: 34430
Change-Id: Ia57b92762a2de83c3bdb1b5e74c0e6d7ce9db309