[epiphany/mcatanzaro/thumbnail-background-position] Add comment requested by Tobias

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 6dfe56e1ba5c1b9f1bd6a41294945ee3c80b547b
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Tue Aug 6 12:27:37 2019 -0500

    Add comment requested by Tobias

 src/resources/about.css | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/resources/about.css b/src/resources/about.css
index 91c3715fc..4bb6209f3 100644
--- a/src/resources/about.css
+++ b/src/resources/about.css
@@ -287,6 +287,9 @@ html.epiphany-html {
     text-align: center;
 }
 
+/* Note: this CSS is adjusted from Ephy.Overview.Item.setThumbnailPath()
+ * in overview.js.
+ */
 .overview-thumbnail {
     height: 160px;
     display: block;