Clean-up and update developer guide to fix generated code examples

- Generated code by Amazon Q was in many case incorrect. Update the
code examples to working examples
- Add picture of custom view created by code examples
- Add notes on examples in respect of purpose and limitations

Signed-off-by: Bernd Hufmann <bernd.hufmann@ericsson.com>

Author: bhufmann

README.md

@@ -285,7 +285,7 @@ yarn playwright test --retries <retries>
 
 ## External API
 
-VSCode Trace Extension provides an external API for adopter extensions. For comprehensive documentation on using the external API, including method references and usage examples, see the [Developer Guide](DEVELOPER-GUIDE.md).
+VSCode Trace Extension provides an external API for adopter extensions. For comprehensive documentation on using the external API, including method references and usage examples, see the [Developer Guide](doc/DEVELOPER-GUIDE.md).
 
 ### Remote SSH Support