euler benchmark documentation

docs/tools/bench.md

@@ -21,6 +21,7 @@ The current benchmarks are:
 * `digial-root`: Computes the digital root of the input number.
 * `eight-queens`: Counts the number of solutions for *n* queens problem, a generalization of [Eight queens puzzle][eight_queens].
 * `euclid`: Calculates the greatest common divisor between two large numbers using the [Euclidean Algorithm][euclid] with a helper function for the modulo operator.
+* `euler`: Approximates [Euler's number][euler] using the Taylor series.
 * `fact`: Prints the factorial of *n*, computing it recursively.
 * `factors`: Print the factors of the *n* using the [trial division][trialdivision] method.
 * `fib`: Calculate the *n*th Fibonacci number by allocating and filling an [array](../lang/memory.md) of numbers up to that point.
@@ -77,3 +78,4 @@ Credit for several of these benchmarks goes to Alexa VanHattum and Gregory Yaune
 [uparrow]: https://en.wikipedia.org/wiki/Knuth%27s_up-arrow_notation
 [riemann]: https://en.wikipedia.org/wiki/Riemann_sum
 [mandelbrot]: https://en.wikipedia.org/wiki/Mandelbrot_set
+[euler]: https://en.wikipedia.org/wiki/E_(mathematical_constant)