HACKING.md: Fixed filename spelling.
HACKING.md: Fixed filename spelling.

Solinea/goldstone-server,Solinea/goldstone-server,Solinea/goldstone-server,slashk/goldstone-server,slashk/goldstone-server,Solinea/goldstone-server,Solinea/goldstone-server,slashk/goldstone-server,slashk/goldstone-server,slashk/goldstone-server