Update Ash strings to use sentence case

ash/ash_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!--
 This file contains the strings for ash.
 -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       output_all_resource_defines="false" source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/ash_strings.h" type="rc_header">
@@ skipping 119 matching lines @@
       nontranslateable parts and create placeholders for them. -->
 
       <!-- TODO(zork): Only include these in Aura builds -->
       <message name="IDS_ASH_SHELF_APP_LIST_LAUNCHER_TITLE" desc="The title used for the Ash Launcher in the Shelf (not mentioning 'Apps' since this is a general launcher).">
         Launcher
       </message>
       <message name="IDS_ASH_SHELF_APP_LIST_LAUNCHER_SYNCING_TITLE" desc="The title used for the Ash Launcher in the Shelf to indicate loading/syncinc apps.">
         Launcher (syncing apps...)
       </message>
       <message name="IDS_ASH_SHELF_OVERFLOW_NAME" desc="The title used for the Ash overflow button in the shelf">
-        Overflow Button
+        Overflow button
       </message>
       <message name="IDS_ASH_SHELF_CONTEXT_MENU_AUTO_HIDE" desc="Title of the menu item in the context menu for auto-hiding the shelf when the current window is not maximized">
         Autohide shelf
       </message>
       <message name="IDS_ASH_SHELF_CONTEXT_MENU_POSITION" desc="Title of the menu item in the context menu for aligning the shelf">
         Shelf position
       </message>
       <message name="IDS_ASH_SHELF_CONTEXT_MENU_ALIGN_BOTTOM" desc="Title of the menu item in the context menu for aligning the shelf to the bottom of the screen">
         Bottom
       </message>
       <message name="IDS_ASH_SHELF_CONTEXT_MENU_ALIGN_LEFT" desc="Title of the menu item in the context menu for aligning the shelf to the left of the screen">
         Left
       </message>
       <message name="IDS_ASH_SHELF_CONTEXT_MENU_ALIGN_RIGHT" desc="Title of the menu item in the context menu for aligning the shelf to the right of the screen">
         Right
       </message>
       <message name="IDS_ASH_SHELF_ACCESSIBLE_NAME" desc="The accessible name of the shelf.">
         Shelf
       </message>
 
       <message name="IDS_ASH_KEYBOARD_OVERLAY_TITLE" desc="The title of the keyboard overlay.">
-        Keyboard Overlay
+        Keyboard overlay
       </message>
 
       <message name="IDS_ASH_LEARN_MORE" desc="Text of Learn more links.">
         Learn more
       </message>
 
       <!-- Status tray items -->
       <message name="IDS_ASH_STATUS_TRAY_ACCESSIBLE_DESCRIPTION" desc="The accessible description of the status tray and the information on it.">
         Status tray, time <ph name="time">$1<ex>9:50</ex></ph>, <ph name="battery">$2<ex>Battery is full.</ex></ph>
       </message>
@@ skipping 228 matching lines @@
 
       <!-- ChromeOS-specific strings -->
       <if expr="chromeos">
         <part file="ash_chromeos_strings.grdp" />
       </if>
 
     </messages>
   </release>
 </grit>