Update README
Revert "Monkey patch Issue model to prevent subtasks from updating parent tasks."

This reverts commit 8fb070fb5f0aed8ef3f317fd301f03f283c3482e.

Not needed as we'll use the patch
Revert "Patch parent tasks and monkey patch Better Gantt Chart plugin to work with the patch."

This reverts commit eac2568fea2d4414309b9eec46176ac3c283bbbf.

No need for better gantt chart plugin anymore