Improve the description of square root problem

Continued from exercism/problem-specifications.

Here’s what I think would be a better description - although this is just a rough draft:

- Given a natural radicand, return its square root.
+ Given a perfect square radicand, return its square root.

Note that the term "radicand" refers to the number for which the root is to be determined. That is, it is the number under the root symbol.

Check out the Wikipedia pages on [square root]( and [methods of computing square roots](

Recall also that natural numbers are positive real whole numbers (i.e. 1, 2, 3 and up).

I agree with this change, and I think it should be made absolutely clear what it entails (aka: every input will be a perfect square and thus every output will be an integer, not a fraction).