Better document and/or improve tracing config precedence

With the introduction of per-route tracing configuration, the precedence is:
- [runtime tracing settings](https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_conn_man/runtime#runtime)
- [per-route settings](https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/route/v3/route_components.proto.html?highlight=random_sampling#config-route-v3-tracing)
- [per-connection manager settings](https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/filters/network/http_connection_manager/v3/http_connection_manager.proto#extensions-filters-network-http-connection-manager-v3-httpconnectionmanager-tracing)

I think the documentation could be structured better.

1. The [Tracing overview](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/observability/tracing) section links to the runtime setting, even though it's the coarsest configuration mechanism and doesn't allow for per-route configuration.
2. The 3 configs documentations (linked above) would do better to link to each other, and the overview documentation would do better to link to all of them.

P.S. re (1) I'm not sure it's even intentional. Perhaps the desired outcome here is that runtime settings, being less specific, should not take precedence over per-route settings?