update design/develop link icons to 2x for high res display

Change-Id: I09560c395088e0f8d835199a6eb4267af50bddaa
diff --git a/tools/droiddoc/templates-sdk/assets/css/default.css b/tools/droiddoc/templates-sdk/assets/css/default.css
index 7f57a8e..4573af3 100644
--- a/tools/droiddoc/templates-sdk/assets/css/default.css
+++ b/tools/droiddoc/templates-sdk/assets/css/default.css
@@ -2627,11 +2627,13 @@
 a.notice-developers div,
 a.notice-designers div {
   min-height:40px;
-  background:url('../images/styles/notice-developers.png') no-repeat 10px 10px;
+  background:url('../images/styles/notice-developers@2x.png') no-repeat 10px 10px;
+  background-size:40px 40px;
   padding:10px 10px 10px 60px;
 }
 a.notice-designers div {
-  background:url('../images/styles/notice-designers.png') no-repeat 10px 10px;
+  background:url('../images/styles/notice-designers@2x.png') no-repeat 10px 10px;
+  background-size:40px 40px;
 }
 a.notice-developers:hover,
 a.notice-designers:hover {