doc: Add GCP Deployment Guide

[ghanshyam2005singh]

Describe the issue

Currently there is no KubeStellar GCP Deployment Guide in docs. Add a proper guide for GCP Deployment.

Want to contribute?

• I would like to work on this issue.

[ghanshyam2005singh]

/assign

[github-actions]

👋 Hello! @ghanshyam2005singh Welcome to the Kubestellar.

We're excited to have you here! Please make sure to check out our Contribution Guide and feel free to join our Slack channel for any questions.