Update `E2001_E2002.md` to suggest needed setting

[HoroTW]

Add a note that legacy entity attributes must (I'm not entirely sure if it is always the case but for me and a friend it was the case [Devices from 2022 and 2024]) be active for some attributes.

Because I'm not entirely sure I worded it as a suggestion.

Note: Of course we tried to set the device specific setting Legacy to false but we also needed to change the setting in Z2M.