message: Document network message and event tracing in `README.md`
diff: @@ -134,7 +134,7 @@ RUST_LOG=info cargo run --release -- validator resources/local/config.toml
  If the environment variable is unset, it is equivalent to setting `RUST_LOG=error`.
  -#### Log message format
  +### Log message format
  A typical log message will look like:
  @@ -149,7 +149,7 @@ This is comprised of the following parts:
  * filename and line number of the source of the message
  * message
  -#### Filtering log messages
  +### Filtering log messages
  `RUST_LOG` can be set to enable varying levels for different modules. Simply set it to a comma-separated list of
  `module-path=level`, where the module path is as shown above in the typical log message, with the end truncated to suit.
  @@ -161,6 +161,24 @@ modules in `components`, and `warn` level for the remaining codebase:
  RUST_LOG=casper_node::components::small=trace,casper_node::comp=info,warn
  ```
  +### Logging network messages and tracing events
  +
  +Special logging targets exist in `net_in` and `net_out` which can be used to log every single network message leaving or
  +entering a node when set to trace level:
  +
  +```
  +RUST_LOG=net_in::TRACE,net_out::TRACE
  +```
  +
  +All messages in these logs are also assigned a unique ID that is different even if the same message is sent to multiple
  +nodes. The receiving node will log them using the same ID as the sender, thus enabling the tracing of a message across
  +multiple nodes provided all logs are available.
  +
  +Another helpful logging feature is ancestor logging. If the target `dispatch` is set to at least debug level, events
  +being dispatched will be logged as well. Any event has an id (`ev`) and may have an ancestor (`a`), which is the previous
  +event whose effects caused the resulting event to be scheduled. As an example, if an incoming network message gets
  +asssigned an ID of `ev=123`, the first round of subsequent events will show `a=123` as their ancestor in the logs.
  +
  ## Debugging
  Some additional debug functionality is available, mainly allowed for inspections of the internal event queue.
  @@ -187,7 +205,7 @@ $ jq < queue_dump.json
  }
  ```
  -#### jq Examples
  +### jq Examples
  Dump the type of events:
  