Improve inequality for "a" in Shor's Algorithm documentation (Qiskit/qiskit-aqua#1133)
Improve inequality for "a" in Shor's Algorithm documentation (Qiskit/qiskit-aqua#1133)

* Improve inequality for "a" in Shor's Algorithm

* change inequality to 1 < a < N
QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py