To add documentation for a systemd service, you can create a systemd unit file with the necessary information and then add comments to explain the purpose and configuration options of the service. Here's an example of how you can add documentation for the TabbyML service:

[Unit]
Description=TabbyML Server Service
After=network.target

# Documentation:
# - This service runs the TabbyML server.
# - It depends on the network being available.

[Service]
Type=exec
User=stephen
Environment="MODEL=TabbyML/StarCoder-7B"
Environment="DEVICE=rocm"
ExecStart=/usr/local/bin/tabby-rocm-$version-$device serve --model $MODEL --device $DEVICE
SyslogIdentifier=tabby
StandardOutput=file:/home/stephen/.tabby/service.log
StandardError=file:/home/stephen/.tabby/error.log

# Documentation:
# - Type: exec
# - User: stephen
# - Environment variables: MODEL, DEVICE
# - ExecStart: command to start the TabbyML server
# - SyslogIdentifier: identifier for syslog
# - StandardOutput: path to the service log file
# - StandardError: path to the error log file

[Install]
WantedBy=default.target

# Documentation:
# - This service is enabled by default.