Clarify Node Usage with Allocation Layer in Documentation

[Fati-Mon]

What
It is necessary to clearly specify which nodes are only applicable when the allocation layer is enabled.

Why
The current documentation does not clearly address this distinction. While it’s briefly mentioned in the 'Usage' section, it may not be easily understood by the user. Additionally, the mention of user_demand, which can be used with or without allocation, might lead to confusion.

How
Include additional clarification under the 'Nodes' sections for Flow and Level Demand. Consider adding an asterisk in the Validation table as well, to avoid the impression that these two nodes can be used regardless of whether the allocation layer is on or off.