docs(typeahead): add typeahead-on-select callback parameters

Closes #2047

Author: bekos

src/typeahead/docs/readme.md

@@ -40,7 +40,7 @@ The typeahead directives provide several attributes:
    _(Defaults: 1)_ :
    Minimal no of characters that needs to be entered before typeahead kicks-in
 
-* `typeahead-on-select` <i class="glyphicon glyphicon-eye-open"></i>
+* `typeahead-on-select($item, $model, $label)`
    _(Defaults: null)_ :
    A callback executed when a match is selected