fix: Add IRSA cross-account deployment guide

[alezander86]

Description

Add new documentation for cross-account deployment using IRSA (IAM Roles for Service Accounts) in KubeRocketCI. The guide provides comprehensive instructions for setting up secure deployments across AWS accounts, including:

• IAM roles and policies configuration for both accounts
• Cluster connection setup
• Service account annotations
• ArgoCD integration
• Deployment flow configuration
• Diagram

Fixes #(issue)

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Followed all steps in a test environment with two AWS accounts
• Verified all IAM roles and policies configurations
• Successfully connected remote cluster using IRSA
• Tested deployment flow with sample application
• Verified ArgoCD integration and cluster status
• Validated all provided commands and configurations

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Pull Request contain one commit. I squash my commits.