Clarify to use Title Case in translations

Bug: b/171901437
Change-Id: Id0785abc0161a1f4f23e85050ab7f3c4f6007408
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2515682Reviewed-by: Rayan Kanso <rayankans@chromium.org>
Commit-Queue: Richard Knoll <knollr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823504}

chrome/app/generated_resources.grd

@@ -8613,12 +8613,12 @@ Please help our engineers fix this problem. Tell us what happened right before y
         </message>
       </if>
       <if expr="use_titlecase">
-        <message name="IDS_NOTIFICATION_MUTED_TITLE" desc="Title of a notification showing how many new notifications are currently hidden. The number is always greater than zero.">
+        <message name="IDS_NOTIFICATION_MUTED_TITLE" desc="In Title Case: Title of a notification showing how many new notifications are currently hidden. The number is always greater than zero.">
           {MUTED_NOTIFICATIONS_COUNT, plural,
             =1 {New Notification}
             other {# New Notifications}}
         </message>
-        <message name="IDS_NOTIFICATION_MUTED_ACTION_SHOW" desc="Action button text to show the content of previously muted notifications.">
+        <message name="IDS_NOTIFICATION_MUTED_ACTION_SHOW" desc="In Title Case: Action button text to show the content of previously muted notifications.">
           {MUTED_NOTIFICATIONS_COUNT, plural,
             =1 {Show}
             other {Show All}}