[accerciser] Document new python-xlib dependency

[Samuel Thibault <sthibaul src gnome org>]

commit e0a5ff8bdac10f1a0f045bc1fd59fce690ac0f80
Author: Samuel Thibault <samuel thibault ens-lyon org>
Date:   Wed Jan 8 16:17:47 2020 +0100

    Document new python-xlib dependency
    
    Fixes #11

 README | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/README b/README
index c2f8e4a..d1351aa 100644
--- a/README
+++ b/README
@@ -84,16 +84,18 @@ As Accerciser uses pygobject, you'll need to have the following libraries:
     pygobject
     appstream-glib-devel
     yelp-tools
+    python3-xlib
 
   On a Debian based distro:
 
     python >= 2.4
-    python-pyatspi >= 1.9.0
+    python3-pyatspi >= 1.9.0
     at-spi2 >= 2.1.5
     libgconf2-dev
-    python-gobject
+    python3-gobject
     appstream-util
     yelp-tools
+    python3-xlib
     
   To use the Python console plugin, you must hve IPython installed.