* Correcting bug on Documentation Page : Byteswapping

* Changing name of variable

DOC:  Add description of overflow errors

Change `np.power` -> `numpy.power` to make it reference
the function's documentation

Unlike Python, NumPy integers have fixed sizes. This can lead to
confusion when a integer overflow occurs and users expect NumPy integer
types to behave similarily to Python integers. This commit explains
integer overflow, an example and potential work arounds.