Add note about Repo.get
cd to app path before of run mix
Revert "Upgrade ecto version"

This reverts commit 97d0d4a997c148753802debbf49a82dd454fb310.
Revert "Rename schema to dataset"

This reverts commit 705b0e6af2388c7c12c792a342bd5e9f079a7a5d.