Add Integration for OpenLIT and a OpenTelemetry guide in Monitoring section

[patcher9]

This PR does two things

• Adds OpenLIT to Integrations which talks about monitoring Milvus with OpenTelemetry (OpenLIT provides auto-instrumentation for monitoring Milvus operations via the SDK)
• Creates a new page under Monitoring for OpenTelemetry and that doc has mostly similar content to what I added in the Integration doc

I would really appreciate some guidance on whats the best way to update the two docs