chore(readme): update README.md for global options

Add an example of specifying a global config value

Author: BaconSoap

README.md

@@ -88,7 +88,7 @@ myAppModule.controller('MyController', function($scope) {
 </select>
 ```
 
-Some time it may make sense to specify the options in the template file.
+Some times it may make sense to specify the options in the template file.
 
 ```html
 <select ui-select2="{ allowClear: true}" ng-model="select2">
@@ -98,6 +98,14 @@ Some time it may make sense to specify the options in the template file.
 </select>
 ```
 
+To define global defaults, you can configure the `uiSelect2Config` injectable:
+
+```javascript
+myAppModule.run(['uiSelect2Config', function(uiSelect2Config) {
+	uiSelect2Config.placeholder = "Placeholder text";
+}]);
+```
+
 ## Working with ng-model
 
 The ui-select2 directive plays nicely with ng-model and validation directives such as ng-required.