✨ feat(server): Add startup script (#63)

## Description

**What issue are you solving (or what feature are you adding) and how
are you doing it?**

We start the container using supervisord, which is limiting as the user
has no way of telling the container what game to run. So, the idea is to
run like so: `docker run... ghcr.io/netrisdotme/netris/server:<tag>
netris-proton /game/yourgame.exe`


Co-authored by @djpremier

.scripts/supervisord.conf

@@ -5,6 +5,9 @@ loglevel=info
 logfile=/tmp/supervisord.log
 pidfile=/tmp/supervisord.pid
 
+[include]
+files = /etc/supervisord.d/*.ini
+
 [program:entrypoint]
 command=/etc/entrypoint.sh
 logfile=/tmp/entrypoint.log