docs(locators): add info on interpolation markers for by.binding

See #1480

Author: juliemr

lib/locators.js

@@ -78,7 +78,12 @@ ProtractorBy.prototype.addLocator = function(name, script) {
 };
 
 /**
- * Find an element by binding.
+ * Find an element by binding. Does a partial match, so any elements bound to
+ * variables containing the input string will be returned.
+ *
+ * Note: For AngularJS version 1.2, the interpolation brackets, usually {{}},
+ * are allowed in the binding description string. For Angular version 1.3, they
+ * are not allowed, and no elements will be found if they are used.
  *
  * @view
  * <span>{{person.name}}</span>
@@ -91,6 +96,13 @@ ProtractorBy.prototype.addLocator = function(name, script) {
  * var span2 = element(by.binding('person.email'));
  * expect(span2.getText()).toBe('[email protected]');
  *
+ * // You can also use a substring for a partial match
+ * var span1alt = element(by.binding('name'));
+ * expect(span1alt.getText()).toBe('Foo');
+ *
+ * // This works for sites using Angular 1.2 but NOT 1.3
+ * var deprecatedSyntax = element(by.binding('{{person.name}}'));
+ *
  * @param {string} bindingDescriptor
  * @return {{findElementsOverride: findElementsOverride, toString: Function|string}}
  */