[jquery/findTestSubject] added docs

src/ui/public/jquery/findTestSubject.js

@@ -1,5 +1,44 @@
 module.exports = function bindToJquery($) {
 
+  /**
+   * Find elements with the `data-test-subj` attribute by the terms in that attribute.
+   *
+   * Find all of the element inside $el with the "saveButton" subject.
+   *
+   * ```js
+   * var $button = $el.findTestSubject('saveButton');
+   * ```
+   *
+   * Find all of the elements with either "saveButton" or "cancelButton"
+   *
+   * ```js
+   * var $buttons = $.findTestSubject('saveButton', 'cancelButton');
+   * ```
+   *
+   * Find all of the elements with a subject that decent from another subject
+   *
+   * ```js
+   * var $button = $.findTestSubject('savedObjectForm saveButton');
+   * ```
+   *
+   * Find all of the elements which have both subjects
+   *
+   * ```js
+   * var $input = $.findTestSubject('smallButton&saveButton');
+   * ```
+   *
+   * @return {jQueryCollection}
+   */
+  $.findTestSubject = function () {
+    return findTestSubject.apply($(document.body), arguments);
+  };
+
+  /**
+   * Just like $.findTestSubject, except only finds elements within another element.
+   * @return {jQueryCollection}
+   */
+  $.fn.findTestSubject = findTestSubject;
+
   function findTestSubject(/* ...subjectSelectors */) {
     var subjectSelectors = [].slice.apply(arguments);
     var $els = $();
@@ -16,9 +55,4 @@ module.exports = function bindToJquery($) {
     return $els;
   };
 
-  $.fn.findTestSubject = findTestSubject;
-  $.findTestSubject = function () {
-    return findTestSubject.apply($(document.body), arguments);
-  };
-
 };