Update environment variable for log level (#749)

`OPEN_CLOUD_LOG_LEVEL` is not the correct name

Author: wsw70

docs/admin/configuration/logging.md

@@ -12,7 +12,7 @@ Logging helps monitor OpenCloud’s health and diagnose issues. Log output varie
 
 ## Log Levels
 
-Set the global log level using the `OPEN_CLOUD_LOG_LEVEL` environment variable. You can also override it per service using service-specific variables. Default is `error`.
+Set the global log level using the `OC_LOG_LEVEL` environment variable. You can also override it per service using service-specific variables. Default is `error`.
 
 ## The log levels are