* doc/manual: Add 'Debugging Nix' section
This commit adds a new 'Debugging Nix' section to the Nix manual. It provides instructions on how to build Nix with debug symbols and how to debug the Nix binary using debuggers like `lldb`.
Co-authored-by: Jörg Thalheim <Mic92@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
