Mention that deletion of QNetworkReply is users responsibility in get()/post()

These could have a note that user is responsible for deleting the reply once it has finished:
https://doc.qt.io/qt-6/qnetworkaccessmanager.html#get
https://doc.qt.io/qt-6/qnetworkaccessmanager.html#post

There is a note in Detailed Description which could maybe be duplicated there:

Note: After the request has finished, it is the responsibility of the user to delete the QNetworkReply object at an appropriate time. Do not directly delete it inside the slot connected to finished(). You can use the deleteLater() function.