Document how to skip external library code when debugging the rails server
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Would be useful if there was documentation showing how to skip external library code when debugging the rails server using `rdgb`.
When I'm debugging I need to add `RUBY_DEBUG_SKIP_PATH=/.asdf/` to the ENV to prevent stepping into any external code installed by `asdf`
example:
`gdk stop rails-web && RUBY_DEBUG_SKIP_PATH=/.asdf/ GITLAB_RAILS_RACK_TIMEOUT_ENABLE_LOGGING=false PUMA_SINGLE_MODE=true rdbg --open -c bin/rails server`
I think the only document that shows how to debug with rdgb is [vs_code_debugging.md](doc/development/vs_code_debugging.md)
~documentation ~"docs::improvement"
issue