Create Examples Documentation for `electricpy.vipf`

[engineerjoe440]

Right now, the general solver electricpy.vipf is a little lack-luster, and could really benefit from some examples to help inform users how it can be used to solve for the various quantities.

Should just be a matter of adding an Examples section to the acpiv docstring; for e.g.,

Examples
--------
>>> import electricpy as ep
>>> V, I, PF = ep.vipf(V=<something>, I=<something-else>)
>>> print(PF)
<quantity>
>>> V, I, PF = ep.vipf(I=<something>, PF=<something-else>)
>>> ep.cprint(V)
<quantity>
>>> V = ep.vipf(I=<something>, PF=<something-else>, find="V")
>>> ep.cprint(V)
<quantity>

Also worth noting is that there's a typo that could easily be corrected: "poer" should be "power" :stuck_out_tongue_winking_eye: :