Commented the env vars and mentioned that they are optional

Author: javiereguiluz

setup/web_server_configuration.rst

@@ -122,10 +122,10 @@ and increase web server performance:
         ErrorLog /var/log/apache2/project_error.log
         CustomLog /var/log/apache2/project_access.log combined
         
-        SetEnv APP_ENV prod
-        SetEnv APP_SECRET <app-secret-id>
-        SetEnv DATABASE_URL "mysql://db_user:db_pass@host:3306/db_name"
-        
+        # optionally set the value of the environment variables used in the application
+        #SetEnv APP_ENV prod
+        #SetEnv APP_SECRET <app-secret-id>
+        #SetEnv DATABASE_URL "mysql://db_user:db_pass@host:3306/db_name"
     </VirtualHost>
 
 .. tip::