Update file README.md

openstack-infrastructure-as-code-automation/clouds/g2/ostrava/general/terraform/README.md

+## Pre-requisites
+ * Linux/Mac/WSL2 terminal
+ * BASH shell
+ * installed terraform ([how?](https://developer.hashicorp.com/terraform/tutorials/aws-get-started/install-cli))
+ * e-INFRA OpenStack cloud personal/group project granted.
+ * downloaded application credentials from OpenStack Horizon dashboard ([how?](https://docs.e-infra.cz/compute/openstack/how-to-guides/obtaining-api-key/)) and store as text file `project_openrc.sh.inc`.
+
+
 # Terraform demonstration
 
 This Terraform module is able to demonstrate creation of two most used cloud infrastructure patterns: