docs: Move examples that are more like test cases to the new tests/ directory; add better example configurations (#3069)

* chore: Move examples that are more like test cases to the new `tests/` directory

* chore: Stash

* feat: Add better examples for EKS managed node groups

* chore: Add better examples for self-managed node groups

* chore: Update docs and correct `nodegroup` to `node group`

tests/eks-managed-node-group/versions.tf

@@ -0,0 +1,10 @@
+terraform {
+  required_version = ">= 1.3.2"
+
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = ">= 5.40"
+    }
+  }
+}