[gnome-software] Remove reference to obsolete Ubuntu review plugin from README

[Richard Hughes <rhughes src gnome org>]

commit 1b11e2a1b17b41f387e3ba3bdbaa59e006945749
Author: Robert Ancell <robert ancell canonical com>
Date:   Thu Mar 7 12:12:05 2019 +1300

    Remove reference to obsolete Ubuntu review plugin from README

 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/README.md b/README.md
index f20fea82..c40a273c 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ Plugins are provided for:
  - Traditional package installation via PackageKit (e.g. Debian package, RPM).
  - Next generation packages: [Flatpak](https://flatpak.org/) and [Snap](https://snapcraft.io/).
  - Firmware updates.
- - Ratings and reviews ([ODRS](https://odrs.gnome.org/) and Ubuntu reviews).
+ - Ratings and reviews using [ODRS](https://odrs.gnome.org/).
 
 Software supports showing metadata that closely matches the 
[AppStream](https://www.freedesktop.org/wiki/Distributions/AppStream/) format.