Feature Request: Adding @generated to header of exported requirements files

[aqeelat]

• I have searched the issues of this repo and believe that this is not a duplicate.
• I have searched the FAQ and general documentation and believe that my question is not already covered.

Feature Request

We benefited greatly from python-poetry/poetry#2773 and I think adding it to the exported requirements files would be a great idea as well.

I would be happy to tackle this.