Improve comment on font sample string

Bug: 123661124
Bug: 128925509
Change-Id: I54b77fdf84b0b175707012855497c6b50b628b6d
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 184296a..10067c8 100755
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -81,7 +81,8 @@
     <!-- Title of a page that shows the user the preview of a wallpaper associated with a theme [CHAR_LIMIT=20] -->
     <string name="preview_name_wallpaper">Wallpaper</string>
 
-    <!-- Title text for previewing a font [CHAR LIMIT=30] -->
+    <!-- Header sample text used to preview the look of a particular font, we show samples of
+        uppercase and lowercase characters and numbers. [CHAR LIMIT=30] -->
     <string name="font_card_title">ABC • abc • 123</string>
 
     <!-- Body text for previewing a font [CHAR LIMIT=160] -->