Update 01-prerequisites.md

Prerequisites updated to cover Azure Free Trial scenario.

docs/01-prerequisites.md

@@ -2,7 +2,7 @@
 
 ## Microsoft Azure
 
-This tutorial leverages the [Microsoft Azure](https://azure.microsoft.com) to streamline provisioning of the compute infrastructure required to bootstrap a Kubernetes cluster from the ground up. [Sign up](https://azure.microsoft.com/en-us/free/) for $200 in free credits.
+This tutorial leverages the [Microsoft Azure](https://azure.microsoft.com) to streamline provisioning of the compute infrastructure required to bootstrap a Kubernetes cluster from the ground up. [Sign up](https://azure.microsoft.com/en-us/free/) for $200 in free credits. In Azure Free Trial there is a limit of 4 Cores available, therefore tutorial instructions must be changed to create 4 nodes instead of 6 (2 controllers and 2 workers).
 
 [Estimated cost](https://azure.microsoft.com/en-us/pricing/calculator/) to run this tutorial: $0.4 per hour ($10 per day).