Mixing description to configure fields in SN7

[PhilipPartsch]

Describe the bug
Documentation of ubcode does not describe howto configure a project with sphinx-needs 7 fields.

https://ubcode.useblocks.com/usage/ubproject.html#need-types

[chrisjsewell]

Yes I purposefully left that out, when adding the features; since they were added before even sphinx-needs v7 was released.

But now we should consider adding them, but in a way that is not too confusing to users (noting what works in <7 and what is for >= 7)