Place "rootURL" in correct location

[notmessenger]

This project uses semver, please check the scope of this pr:

• [x] #none# - documentation fixes and/or test additions
• [ ] #patch# - backwards-compatible bug fix
• [ ] #minor# - adding functionality in a backwards-compatible manner
• [ ] #major# - incompatible API change

CHANGELOG

• Update location of rootURL configuration option messed up during prior Ember CLI upgrade

[juwara0]

Approved