Hwo to configuration for opentracing

```
tracing:
enabled: false
jaeger:
serviceName: ""
disabled: false
rpc_metrics: false
tags: []
sampler: null
reporter: null
headers: null
baggage_restrictions: null
throttler: null
```

https://github.com/matrix-org/dendrite/tree/master/docs/tracing
page not found

Start by checking the repository's docs/tracing directory and compare it with the configuration block shown in the issue. Confirm the current OpenTracing or Jaeger configuration guidance and replace or repair the broken documentation link; done means the page is reachable and explains the displayed settings.

Written by the indexing model from the issue text.