"Add label" -> "Add folder"

Change-Id: If86cc24e0ed76a0c087c9ecd02b273a78a797a74
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 054d20c..d350098 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -438,7 +438,7 @@
     <!-- Conversation view -->
     <!--  Text anchor for control to add / change labels on a conversation when
           viewing it. [CHAR LIMIT=40] -->
-    <string name="add_label">Add label</string>
+    <string name="add_label">Add folder</string>
 
     <!-- New Message notification text that appears over conversation view on incoming message. [CHAR LIMIT=30] -->
     <string name="new_incoming_messages_one">New message from <xliff:g id="sender">%s</xliff:g>. Show.</string>