fixed typo in README.md (#169)

Author: manelet

README.md

@@ -260,7 +260,7 @@ You can use your own messages. Here is the default messages object:
     searchPlaceholder: "Search...",
     noItemsMessage: "No Items...",
     noneSelectedMessage: "None Selected",
-    selectedMessage: "delected",
+    selectedMessage: "selected",
     selectAllMessage: "Select All",
     clearAllMessage: "Clear All",
     disabledItemsTooltip: "You can only select 1 file"