Fixed typo in language file

Author: Sam

js/languages/en-US.json

@@ -259,7 +259,7 @@
   "UploadAvatar": "Select Avatar",
   "NewAvatar": "Select New Avatar",
   "NewCoverImage": "Select New Cover Image",
-  "CheckExchanges": "Contacting vendors's node and updating exchange rates if applicable...",
+  "CheckExchanges": "Contacting vendor's node and updating exchange rates if applicable...",
   "Transactions": "Transactions",
   "Purchases": "Purchases",
   "Sales": "Sales",