Prometheus metrics documentation missing deprecation warnings for queue metrics

[snichme]

Describe the bug
The Prometheus integration documentation at https://lavinmq.com/documentation/prometheus lists the queue metrics ready, ready_bytes, unacked, and unacked_bytes with no deprecation warnings. According to CHANGELOG.md, these metrics are deprecated in favor of RabbitMQ-compatible names and will be removed in the next major version.

Describe your setup
This affects the documentation website at lavinmq.com, not a specific LavinMQ installation.

How to reproduce

1. Visit https://lavinmq.com/documentation/prometheus
2. Look for the metrics ready, ready_bytes, unacked, and unacked_bytes
3. Notice no deprecation warnings are present

Expected behavior
The documentation should clearly indicate which metrics are deprecated and their replacements:

• ready → messages_ready
• ready_bytes → message_bytes_ready
• unacked → messages_unacknowledged
• unacked_bytes → message_bytes_unacknowledged

Suggested fix
Add deprecation warnings to each deprecated metric in the documentation:

DEPRECATED: ready → Use messages_ready instead
DEPRECATED: ready_bytes → Use message_bytes_ready instead
DEPRECATED: unacked → Use messages_unacknowledged instead
DEPRECATED: unacked_bytes → Use message_bytes_unacknowledged instead

Impact
CRITICAL - Users monitoring LavinMQ with Prometheus may build dashboards and alerting rules using the deprecated metric names. These will break when upgrading to the next major version, potentially causing monitoring blind spots in production.

References

• CHANGELOG.md documents the deprecation and new RabbitMQ-compatible names
• The new metric names are already available alongside the deprecated ones