[gnome-calendar] Update README.md

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 88ce5407d52eeae7099040a49f82f1cef50acee4
Author: Roger <sachanroger gmail com>
Date:   Sun Sep 1 20:47:33 2019 +0000

    Update README.md

 README.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/README.md b/README.md
index 28fba382..9629af64 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,8 @@ GNOME Calendar is a simple and beautiful calendar application for GNOME. We give
 a lot of attention to details, and as such, design is an essential and ongoing
 effort.
 
-<a href='https://flathub.org/apps/details/org.gnome.Calendar'><img width='240' alt='Download on Flathub' 
src='https://flathub.org/assets/badges/flathub-badge-i-en.png'/></a>
+[![Flatpak](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Flathub-badge-en.svg/240px-Flathub-badge-en.svg.png)](https://flathub.org/apps/details/org.gnome.Calendar)
+
 
 ## Useful links