Addition of EKS multi-cluster observability example (#155)

* Adding EKS multicluster observability example

* EKS multicluster example - precommit fix

* Corrected the path to an example

* Made the multicluster example simpler

* Pre-commit changes

* Saved the images to Github and linked them in docs

* Comments and language edits

* Fix trailing spaces

* Non-controversial naming and simpler variables

* Added region to the data gathering

* Formatting changes

---------

Co-authored-by: Rodrigue Koffi <bonclay7@users.noreply.github.com>

examples/eks-multicluster/variables.tf

@@ -0,0 +1,46 @@
+variable "eks_cluster_1_id" {
+  description = "Name or ID of the EKS cluster 1"
+  type        = string
+  default     = "eks-cluster-1"
+  nullable    = false
+}
+
+variable "eks_cluster_1_region" {
+  description = "AWS region of the EKS cluster 1"
+  type        = string
+  default     = "us-west-2"
+  nullable    = false
+}
+
+variable "eks_cluster_2_id" {
+  description = "Name or ID of the EKS cluster 2"
+  type        = string
+  default     = "eks-cluster-2"
+  nullable    = true
+}
+
+variable "eks_cluster_2_region" {
+  description = "AWS region of the EKS cluster 2"
+  type        = string
+  default     = "us-west-2"
+  nullable    = true
+}
+
+variable "managed_prometheus_workspace_id" {
+  description = "Amazon Managed Service for Prometheus Workspace ID"
+  type        = string
+  default     = ""
+}
+
+variable "managed_grafana_workspace_id" {
+  description = "Amazon Managed Grafana Workspace ID"
+  type        = string
+  default     = ""
+}
+
+variable "grafana_api_key" {
+  description = "API key for authorizing the Grafana provider to make changes to Amazon Managed Grafana"
+  type        = string
+  default     = ""
+  sensitive   = true
+}