Merge pull request #2 from Mendor/patch-1

typo in usage example in README.md

Author: 0xAX

src/dropdown/README.md

@@ -8,10 +8,10 @@ Usage
 
 ```html
 <dropdown title="my dropdown" ng-model="dropdown_model" open="true">
-    <dropdown-gropup>item1</dropdown-gropup>
-    <dropdown-gropup>item2</dropdown-gropup>
-    <dropdown-gropup>item3</dropdown-gropup>
-    <dropdown-gropup>item4</dropdown-gropup>
+    <dropdown-group>item1</dropdown-group>
+    <dropdown-group>item2</dropdown-group>
+    <dropdown-group>item3</dropdown-group>
+    <dropdown-group>item4</dropdown-group>
 </dropdown>
 ```
 
@@ -27,4 +27,4 @@ Contribution
 TODO
 -------------------------------
 
-1. Add different dropdown types.
+1. Add different dropdown types.