[gnome-calendar] Add info to README

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

commit a8882b441b9faca3976e816f30d8460c9aa4ce3a
Author: Roger <sachanroger gmail com>
Date:   Tue Aug 27 22:23:08 2019 +0000

    Add info to README

 README.md | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/README.md b/README.md
index a9453ef6..28fba382 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,11 @@ 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.
 
-The wiki is [here][1]
+<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>
 
-[1]: https://wiki.gnome.org/Apps/Calendar
+## Useful links
+
+- Homepage: <https://wiki.gnome.org/Apps/Calendar>
+- Report issues: <https://gitlab.gnome.org/GNOME/gnome-calendar/issues/>
+- Donate: <https://www.gnome.org/friends/>
+- Translate: <https://wiki.gnome.org/TranslationProject>
\ No newline at end of file