Update How to add configurations.md

Author: Frooodle

docs/Advanced Configuration/How to add configurations.md

@@ -20,11 +20,11 @@ Environment variables are also supported and would override the settings file
 For example in the settings.yml you have
 
 ```
-system:
+security:
   enableLogin: 'true'
 ```
 
-To have this via an environment variable you would have ``SYSTEM_ENABLELOGIN``
+To have this via an environment variable you would have ``SECURITY_ENABLELOGIN``
 
 The Current list of settings is
 
@@ -142,4 +142,4 @@ Simply add these to the end of your script/file:
       UI_APP_NAVBAR_NAME: Stirling PDF
     ```
   </TabItem>
-</Tabs>
+</Tabs>