message: Add NWNX_SQL_QUERY_METRICS to the SQL Documentation
diff: @@ -69,3 +69,15 @@ __Example__
  ```
  export NWNX_SQL_DATABASE=mymodulename
  ```
  +
  +### NWNX_SQL_QUERY_METRICS
  +
  +Export query execution metrics.
  +
  +The Metrics_InfluxDB plugin and a visualizer like Grafana are required to view these metrics.
  +
  +__Example__
  +
  +```
  +export NWNX_SQL_QUERY_METRICS=true
  +```
  