Fix logging format in Docker image sample file

changelog.d/5620.bugfix

@@ -0,0 +1 @@
+Add missing space in default logging file format generated by the Docker image

docker/conf/log.config

@@ -2,7 +2,7 @@ version: 1
 
 formatters:
   precise:
-   format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s- %(message)s'
+   format: '%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(request)s - %(message)s'
 
 filters:
   context: