docs: update debug logging documentation

Correct out of date component names and add section on using prefix logging.

Author: achingbrain

doc/GETTING_STARTED.md

@@ -250,16 +250,28 @@ If you want to know more about libp2p peer discovery, you should read the follow
 
 ## Debugging
 
-When running libp2p you may want to see what things are happening behind the scenes. You can see trace logs by setting the `DEBUG` environment variable when running in Node.js, and by setting `debug` as a localStorage item when running in the browser. Some examples:
+When running libp2p you may want to see what things are happening behind the scenes. You can see trace logs by setting the `DEBUG` environment variable when running in Node.js, and by setting `debug` as a localStorage item when running in the browser.
+
+You may wish to start with trace logging, then narrow down the scope to just the components you are interested in.
+
+Wildcards in components names are supported (`*`), and components can be excluded by prefxing their name with `-`.
+
+Some examples:
 
 ### Node
 
 ```JavaScript
 # all libp2p debug logs
 DEBUG="libp2p:*" node my-script.js
 
-# networking debug logs
-DEBUG="libp2p:tcp,libp2p:websockets,libp2p:webtransport,libp2p:kad-dht,libp2p:dialer" node my-script.js
+# all libp2p debug logs, maximum detail
+DEBUG="libp2p:*,*:trace" node my-script.js
+
+# all libp2p debug logs including trace logs, exclude yamux
+DEBUG="libp2p:*,*:trace,-libp2p:yamux:*" node my-script.js
+
+# networking debug logs (here TCP and WebSocket transports are configured)
+DEBUG="libp2p:tcp:*,libp2p:websockets:*,libp2p:kad-dht,libp2p:connection-manager:*" node my-script.js
 ```
 
 ### Browser
@@ -269,9 +281,46 @@ DEBUG="libp2p:tcp,libp2p:websockets,libp2p:webtransport,libp2p:kad-dht,libp2p:di
 localStorage.setItem('debug', 'libp2p:*') // then refresh the page to ensure the libraries can read this when spinning up.
 
 // networking debug logs
-localStorage.setItem('debug', 'libp2p:websockets,libp2p:webtransport,libp2p:kad-dht,libp2p:dialer')
+localStorage.setItem('debug', 'libp2p:websockets*,libp2p:webtransport*,libp2p:kad-dht*,libp2p:connection-manager*')
 ```
 
+### Prefix logger
+
+If you are running multiple nodes in the same process (for example during a test run), separating their log output can be difficult.
+
+In this situation you can use the `prefixLogger` from the `@libp2p/logger` module:
+
+```ts
+import { prefixLogger } from '@libp2p/logger'
+import { createLibp2p } from 'libp2p'
+
+const dialer = await createLibp2p({
+  logger: prefixLogger('dialer')
+  // ... other options
+})
+
+const listener = await createLibp2p({
+  logger: prefixLogger('listener')
+  // ... other options
+})
+```
+
+All logs will be prefixed by the string passed to the prefix logger, so later you can do:
+
+```console
+DEBUG=dialer:*,listener:* node ./index.js
+listener:libp2p:transports adding transport @libp2p/tcp +0ms
+dialer:libp2p libp2p is starting +0ms
+listener:libp2p libp2p is starting +0ms
+dialer:libp2p:connection-manager started +0ms
+listener:libp2p:connection-manager started +0ms
+listener:libp2p:transports creating listener for @libp2p/tcp on /ip4/127.0.0.1/tcp/0 +6ms
+dialer:libp2p libp2p has started +7ms
+listener:libp2p libp2p has started +7ms
+```
+
+...and apply component log filters via the `DEBUG` env var as normal, e.g. `DEBUG=listener:libp2p:tcp:*` to just see TCP transport logs for the listener node, etc.
+
 ## React Native
 
 Libp2p can be used in React Native applications. However, there are some limitations and considerations to take into account as not all transports are supported and some of the underlying dependencies may not work as expected. There is on-going work to address these issues, particularly around the support of TCP. For a demo on how to use libp2p in a React Native application, see https://github.com/ipfs-shipyard/js-libp2p-react-native