tooltips.rst: add IMPORTANT NOTE as well as some clarifications

Author: TimurKelman

docs/gui/tooltips.rst

@@ -5,7 +5,15 @@ gui/tooltips
     :summary: Show name and job tooltips near units on map.
     :tags: fort inspection
 
-This script shows "tooltips" following units and/or mouse with job names.
+**IMPORTANT NOTE**: the tooltips will show over any vanilla UI elements!
+
+
+This script shows "tooltips" in two optional modes:
+
+* following the mouse, when a unit is underneath the cursor;
+* following units on the map.
+
+Information shown includes happiness indicator, name, and current job.
 
 Usage
 -----