KEG metrics

## Jobs to be done (optional)

EG generates a markdown file with the metrics they support, the team wants a page with this.
we could automate the process and talk to the team to see if we can add metadata to it.
Another option would be to create our own markdown page with metadata only and include their file directly, e.g.

```
# app/event-gateway/metrics.md
---
metadata goes here
---

{% event_gateway_generated_metrics %} -> this would include the generated file from EG
```

## Definition of done

Page with EG supported metrics generated from source.
This page should be versioned.

## Information

[slack convo](https://kongstrong.slack.com/archives/C089Z3BMC9Z/p1762276354352009)

## Due date (optional)

## Size

M