explain tags

Author: Vladimir Kotal

apiary.apib

@@ -71,7 +71,11 @@ Besides `/suggester` and `/search` endpoints, everything is accessible from `loc
 
 ### adds message to a system [POST]
 
-Usable values for `cssClass` are: `info`, `warning`, `error`
+Usable values for `cssClass` are: `info`, `warning`, `error`.
+This will affect CSS class of the displayed message, leading to different coloring.
+
+The values in the `tags` list can be: `main` (special value for top level message in the whole web application),
+project name and project group name.
 
 The format of `duration` is the same as Java's java.time.Duration class,
 see https://docs.oracle.com/javase/8/docs/api/java/time/Duration.html#parse-java.lang.CharSequence-