Update README for Installation Steps and Cleanup Instructions

[arakashnawin]

Summary

This PR updates the README file to improve clarity and usability for users setting up the observability stack using Prometheus and Grafana on EKS.

Changes Made

1. Installation Steps:

   • Added direct links for downloading and installing AWS CLI, eksctl, and kubectl for user convenience.

2. Cleanup Instructions:

   • Added a confirmation step to check if all resources are correctly deleted.
   • Noted that persistent volume claims (PVCs) may remain after uninstalling the Helm chart and should be manually deleted if not needed.

Testing

• Verified that all links direct users to the correct installation pages.
• Ensured that all commands function as expected.

Please review the changes and let me know if any additional modifications are needed.