Please fix the 'Manage epics in next-gen projects' documentation

Issue Summary

The Manage epics in next-gen projects documentation page is referring to options that are named differently and this is causing confusion.

Specifically:

• The steps and screenshots provided to add or remove/modify issues from epics are saying you should use the options Add to Epic or Change Epic (respectively):
  

• The above options do not actually exist and you have to use Add to parent issue and Change parent issue instead:
  

Workaround.

Use Add to parent issue and Change parent issue in order to add or change/remove an issue from an epic.