[libadwaita] readme: Update demo path

[Alexander Mikhaylenko <alexm src gnome org>]

commit fe0895a9238bbbd22efaa1827f4eb2ba40c76513
Author: Leleat <atule pm me>
Date:   Fri Nov 12 03:14:40 2021 +0100

    readme: Update demo path
    
    Related: https://gitlab.gnome.org/GNOME/libadwaita/-/merge_requests/292

 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/README.md b/README.md
index c66a811a..9d1e5de0 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ ninja -C _build
 There's a C example:
 
 ```sh
-_build/run _build/examples/adwaita-1-demo
+_build/run _build/demo/adwaita-1-demo
 ```
 
 ## Documentation