Typo in 01_foundations/Code.ipynb

[pjgoodall]

In the first plot of the Square and ReLU functions:

ax[0].set_title("Square function")
ax[0].set_xlabel("input")
ax[0].set_ylabel("input")

ylabel is a duplicate of xlabel.

should have been:

ax[0].set_title("Square function")
ax[0].set_xlabel("input")
ax[0].set_ylabel("output")