Add kubescape as a security scanning tool

**Is your idea request related to a problem that you've solved? Please describe.**
A clear and concise description of the problem.

**Describe the best practice**
As part of the Security Best Practices Guide chapter, add *kubescape* as a security scanning OSS tool for EKS clusters.

**Additional context**
[Kubescape](https://github.com/kubescape/kubescape) is one of the fastest-growing Kubernetes security tools. It is an open-source Kubernetes security platform and can scan Kubernetes clusters, container images, YAML files, and Helm charts for security vulnerabilities. Kubescape can detect misconfiguration according to multiple frameworks, like NSA-CISA, MITRE ATT&CK®.