[gnome-calculator] Added basic README with CI links

[Robert Roth <robertroth src gnome org>]

commit 727a8dce12086c2bed40fb73965d4b494ae748d0
Author: Robert Ancell <robert ancell canonical com>
Date:   Fri Jul 6 18:41:01 2018 +0200

    Added basic README with CI links

 README.md | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/README.md b/README.md
new file mode 100644
index 00000000..540035b3
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+[![Build 
Status](https://gitlab.gnome.org/GNOME/gnome-calculator/badges/master/build.svg)](https://gitlab.gnome.org/GNOME/gnome-calculator/pipelines)
+
+This is the source code for the standard GNOME calculator.