Fix class in the example code for text-monospace in docs v4.1

Created by: abhitalks

Utilities > Text > Monospace

The docs say, "Change a selection to our monospace font stack with .text-monospace.", describing the use of the class .text-monospace.

However, the code in the example uses the class .font-monospace as in <p class="font-monospace">This is in monospace</p>.