copy change for browserID field

mkt/account/templates/account/settings.html

@@ -43,7 +43,7 @@
         <div class="form-col">
           <input type="text" disabled value="{{ amo_user.email }}">
           <a href="https://browserid.org/signin" target="_blank">
-            {{ _('Manage Preferences') }}</a>
+            {{ _('Manage Account') }}</a>
         </div>
       </div>