[libadwaita.wiki] Update Testing the stylesheet in GTK demos

[Alexander Mikhaylenko <alexm src gnome org>]

commit b5e9a6ef86f84dcf01f40e15160ebed5bebae7ae
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Sat Mar 12 10:42:04 2022 +0000

    Update Testing the stylesheet in GTK demos

 Testing-the-stylesheet-in-GTK-demos.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/Testing-the-stylesheet-in-GTK-demos.md b/Testing-the-stylesheet-in-GTK-demos.md
index 4d22932..d88471a 100644
--- a/Testing-the-stylesheet-in-GTK-demos.md
+++ b/Testing-the-stylesheet-in-GTK-demos.md
@@ -62,7 +62,7 @@ Alternatively, you can use:
 
 In this case, inspector cannot be used to change the styles.
 
-All the commands above work with `gtk4-widget-factory` as well.
+All of the commands above work with `gtk4-widget-factory` as well.
 
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