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/user-data/rendered/al2023/eks-mng-additional.txt

@@ -0,0 +1,19 @@
+Content-Type: multipart/mixed; boundary="MIMEBOUNDARY"
+MIME-Version: 1.0
+
+--MIMEBOUNDARY
+Content-Transfer-Encoding: 7bit
+Content-Type: application/node.eks.aws
+Mime-Version: 1.0
+
+---
+apiVersion: node.eks.aws/v1alpha1
+kind: NodeConfig
+spec:
+  kubelet:
+    config:
+      shutdownGracePeriod: 30s
+      featureGates:
+        DisableKubeletCloudCredentialProviders: true
+
+--MIMEBOUNDARY--