docs: add self-contained setup reference configs (emulator + nitro) and bold-link buttons

setup/emulator/emulator.service

@@ -0,0 +1,25 @@
+[Unit]
+Description=Habbo Emulator
+
+# Make sure the database has started before the emulator can start
+After=mariadb.service
+Requires=mariadb.service
+
+# If you want to run as a less privileged account, change User below.
+# Make sure that account has the right permissions on the working directory and target folders.
+[Service]
+User=root
+
+# Working directory where config.ini and the JAR live
+WorkingDirectory=/var/www/emulator/Emulator/target
+
+# The launcher script we created below. It is a shell wrapper that calls the JAR.
+ExecStart=/var/www/emulator/Emulator/target/emulator
+
+SuccessExitStatus=143
+TimeoutStopSec=10
+Restart=on-failure
+RestartSec=5
+
+[Install]
+WantedBy=multi-user.target