Update BB primer section and gif

[glassnotes]

Primer needs to be updated to reflect the behaviour of the bus qubit in BB qRAM. It does not, in fact, perform the resetting of the qutrits back to the |wait> state, but rather exits on its own. The qutrits are to be reset by the address qubits that were sent in from the start - they "leave" the system and perform the inverse unitary operation on their way out.