feat(monitoring): add container metrics collection for pod debugging

[amdove]

Description

Expanded the monitoring documentation to provide comprehensive coverage of all container-level metrics collected via cAdvisor and kube-state-metrics. Organized metrics into clear categories (memory, CPU, network, filesystem, lifecycle) with detailed descriptions of each metric's purpose.

Added extensive troubleshooting section with practical PromQL queries for diagnosing:

• Memory issues and OOMKilled pods
• CPU throttling and performance problems
• Network connectivity, throughput, and packet drops
• Disk I/O usage and IOPS bottlenecks
• Container restart patterns and lifecycle issues

Each troubleshooting category includes ready-to-use Grafana queries and key investigation points to help operators quickly diagnose and resolve container resource issues.

Category of change

• Bug fix (non-breaking change which fixes an issue)
• Version upgrade (upgrading the version of a service or product)
• New feature (non-breaking change which adds functionality)
• Build: a code change that affects the build system or external dependencies
• Performance: a code change that improves performance
• Refactor: a code change that neither fixes a bug nor adds a feature
• Documentation: documentation changes
• Breaking change (fix or feature that would cause existing functionality to not work as expected)