message: Expand application configuration docs
diff: @@ -11,19 +11,35 @@ Default configuration values can be found at `config/config.js` and `config/defa
  ## Configuration Options
  ```bash
  +# HTTP
  PORT # Port to listen on
  -MAPBOX_PUBLIC_KEY # Mapbox key if you wish to use `/explore` functionality
  -
  +# Postgresl Configuration
  POSTGRES_USER # Postgres user
  POSTGRES_PASSWORD # Postgres password
  POSTGRES_DATABASE # Postgres database name
  POSTGRES_HOST # Postgres host
  POSTGRES_PORT # Postgres port
  +# Logging
  LOG_NAME # Name attached to JSON log output
  LOG_DESTINATION # Log destination, can be set to file `LOG_DESTINATION=/var/logs/pcio.log` or `stdout` or `perf` (high performance stdout)
  +# Google analytics key
  +GA_KEY
  +
  +# Mapbox key if you wish to use `/explore` functionality
  +MAPBOX_PUBLIC_KEY
  +
  +# Enable pm2/io application monitoring
  +PMX
  +
  +#Inserts optional prometheus monitoring middleware
  +# Express-prom-bundle exposes a '/metrics' endpoint which can be queried by prometheus
  +# This endpoint requires basic auth defined by:
  +PROMETHEUS_USERNAME
  +PROMETHEUS_PASSWORD
  +
  # Application defaults configuration
  NEAREST_RADIUS_DEFAULT,
  NEAREST_RADIUS_MAX,
  