[gnome-text-editor] README: add link to try it out

[Christian Hergert <chergert src gnome org>]

commit 1cc579a7d4edec483a593272e55662ec0a6c0453
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jun 26 19:11:08 2021 -0700

    README: add link to try it out

 README.md | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/README.md b/README.md
index f8817eb..025401e 100644
--- a/README.md
+++ b/README.md
@@ -12,3 +12,7 @@ Text Editor was built as a test application for the development of GTK 4 and Gtk
 
 Everyone has their favorite programming text editors. Text Editor is focused
 on being a great default text editor.
+
+## Try it Out!
+
+You can install our Nightly build from Flatpak using 
[https://nightly.gnome.org/repo/appstream/org.gnome.TextEditor.Devel.flatpakref](org.gnome.TextEditor.Devel.flatpakref).