Merge branch '593-broken-link-to-loki-documentation' into 'master'

Resolve "Broken link to loki documentation"

Closes #593

See merge request openappstack/openappstack!293

docs/maintenance.md

@@ -22,7 +22,13 @@ together with some generic query examples.
 
 ### LogQL query examples
 
-Please also refer to the [LogQL documentation](https://github.com/grafana/loki/blob/master/docs/logql.md).
+Please also refer to the [LogQL documentation](https://github.com/grafana/loki/blob/master/docs/logql%2Emd).
+
+
+Query all apps for errors etc:
+
+    {job=~".*"} |~ "error|fail|exception|fatal"
+    {job=~".*"} |= "level=error"
 
 #### Flux