Change notebook in day_3 numpy to match colab notebook

in-class code block #3

this this code:
```
# Transposing an array
a1 = a.T
print('Reshaped array size :', a1.shape)
print(a1)
```

was changed to:

```
# Transposing an array
a1 = a.T
print('Reshaped array shape :', a1.shape)
print(a1)
```