add 'external-link' class for links that go off-site

Change-Id: I9e78cd6a7cb2ce14e5e15fe43e87b55ac456f302
diff --git a/tools/droiddoc/templates-sdk/assets/css/default.css b/tools/droiddoc/templates-sdk/assets/css/default.css
index 30bdc25..1a4327b 100644
--- a/tools/droiddoc/templates-sdk/assets/css/default.css
+++ b/tools/droiddoc/templates-sdk/assets/css/default.css
@@ -112,6 +112,11 @@
 a:focus,
 a:active {
   color: #33b5e5 !important; }
+  
+a.external-link {
+  background:url('../images/styles/open_new_page.png') no-repeat 100% 50%;
+  padding-right:16px;
+}
 
 img {
   border: none; }