Implement/Review the official K8s cluster security guide

[TAnas0]

Goals:

1. Go over the K8s guide Securing a cluster
2. Implement/check them in the K8s cluster, when possible.
3. Identify how they relate to the DO recommended steps to secure a K8s cluster tackled in Implement/Review the official DO recommended K8s cluster configuration #21
4. Identify what falls under our security responsibility vs. what falls under DO's responsibility

For the sake of reference and high-level view, here is the Table of Contents of the article:

1. Controlling access to the Kubernetes API
   1.1 Use Transport Layer Security (TLS) for all API traffic
   1.2 API Authentication
   1.3 API Authorization
2. Controlling access to the Kubelet
3. Controlling the capabilities of a workload or user at runtime
   3.1 Limiting resource usage on a cluster
   3.2 Controlling what privileges containers run with
   3.3 Preventing containers from loading unwanted kernel modules
   3.4 Restricting network access
   3.5 Restricting cloud metadata API access
   3.6 Controlling which nodes pods may access
4. Protecting cluster components from compromise
   4.1 Restrict access to etcd
   4.2 Enable audit logging
   4.3 Restrict access to alpha or beta features
   4.4 Rotate infrastructure credentials frequently
   4.5 Review third party integrations before enabling them
   4.6 Encrypt secrets at rest
   4.7 Receiving alerts for security updates and reporting vulnerabilities

Things to keep in mind:

• The Managed Elements of K8s: will help you identify what falls under our responsibility vs. that of DO as a provider
• DigitalOcean Kubernetes Security Information

Please detail, in a PR, all the steps followed and keep track of all the commands/manipulations performed.