MD Settings: tweak Accessibility "learn more" button text

chrome/app/settings_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Settings-specific strings (included from generated_resources.grd). -->
 <grit-part>
   <!-- Policy Indicators -->
   <message name="IDS_SETTINGS_CONTROLLED_SETTING_EXTENSION" desc="Text displayed in the controlled settings indicator tooltip when a setting's value is enforced by an extension.">
     This setting is controlled by extension <ph name="NAME">$1<ex>Settings Extension</ex></ph>
   </message>
 
   <!-- Accessibility Page -->
   <message name="IDS_SETTINGS_ACCESSIBILITY" desc="Name of the settings page which displays accessibility preferences.">
     Accessibility
   </message>
-  <!-- TODO(dbeam): why is this "add additional"? Seems redundant. -->
   <message name="IDS_SETTINGS_MORE_FEATURES_LINK" desc="Link which opens page where users can install extensions which provide additional accessibility features.">
-    Add additional accessibility features
+    Add accessibility features
   </message>
   <if expr="chromeos">
     <message name="IDS_SETTINGS_OPTIONS_IN_MENU_LABEL" desc="Label for checkbox which enables showing accessibility options in the system menu.">
       Show accessibility options in the system menu
     </message>
     <message name="IDS_SETTINGS_LARGE_MOUSE_CURSOR_LABEL" desc="Label for checkbox which enables showing a larger mouse cursor than normal.">
       Show large mouse cursor
     </message>
     <message name="IDS_SETTINGS_HIGH_CONTRAST_LABEL" desc="Label for checkbox which enables high-contrast UI.">
       Use high contrast mode
@@ skipping 1131 matching lines @@
       System
     </message>
     <message name="IDS_SETTINGS_SYSTEM_HARDWARE_ACCELERATION_LABEL" desc="Label for the checkbox that forces Chrome to render via hardware acceleration (GPU) when available.">
       Use hardware acceleration when available
     </message>
     <message name="IDS_SETTINGS_SYSTEM_PROXY_SETTINGS_BUTTON" desc="Text for the button that changes a user's network proxy settings.">
       Change proxy settings
     </message>
   </if>
 </grit-part>