MINOR: Update documentation on worldOffset (#1933)

Signed-off-by: Jonathan Stichbury <2533428+nzjony@users.noreply.github.com>

@here/harp-datasource-protocol/lib/TechniqueParams.ts

@@ -827,11 +827,13 @@ export interface MarkerTechniqueParams extends BaseTechniqueParams {
     placements?: string;
 
     /**
-     * World space offset in meters applied to the icon.
+     * World space offset in meters applied to the icon along the ground plane, i.e. tangent
+     * to the local space up vector.
      *
      * @remarks
      * Valid only for icons which have the
-     * "offset_direction" property as an attribute of the data.
+     * "offset_direction" property as an attribute of the data, which specifies an angle in degrees
+     * in which direction the offset should take place, i.e. 0 degrees is north, 90 is east etc.
      */
     worldOffset?: DynamicProperty<number>;
 }