Update instructions.append.md

Clarify that the built-in exponentiation operator ** is equivalent to pow() and therefore doesn't demonstrate an implementation of a square root algorithm, and also note that for the domain of this exercise there are available solutions using only positive integers.

exercises/practice/square-root/.docs/instructions.append.md

@@ -3,10 +3,10 @@
 ## How this Exercise is Structured in Python
 
 
-Python offers a wealth of mathematical functions in the form of the [math module][math-module] and built-ins such as [`pow()`][pow] and [`sum()`][sum].
+Python offers a wealth of mathematical functions in the form of the [math module][math-module] and built-ins such as the exponentiation operator `**`, [`pow()`][pow] and [`sum()`][sum].
 However, we'd like you to consider the challenge of solving this exercise without those built-ins or modules.
 
-While there is a mathematical formula that will find the square root of _any_ number, we have gone the route of having only [natural numbers][nautral-number] (positive integers) as solutions.
+While there is a mathematical formula that will find the square root of _any_ number, we have gone the route of having only [natural numbers][nautral-number] (positive integers) as solutions.  It is possible to compute the square root of any natural number using only natural numbers in the computation.
 
 
 [math-module]: https://docs.python.org/3/library/math.html