Update tutorial.rst

[benthayer]

Fixes this issue

Traceback (most recent call last):
  File "simple.py", line 14, in <module>
    t = np.linspace(0, T, T * sample_rate, False)
  File "<__array_function__ internals>", line 5, in linspace
  File "/.../site-packages/numpy/core/function_base.py", line 113, in linspace
    num = operator.index(num)
TypeError: 'float' object cannot be interpreted as an integer