README.md: add notes about the new 'cmd2' dependency

Change-Id: I314317ab547bc32497839fe70e7a6f6b66bcc8ef
diff --git a/README.md b/README.md
index 3234665..c6ec3db 100644
--- a/README.md
+++ b/README.md
@@ -37,10 +37,11 @@
 - pyscard
 - serial
 - pytlv (for specific card types)
+- cmd2 (for pySim-shell.py)
 
 Example for Debian:
 
-	apt-get install python3-pyscard python3-serial python3-pip python3-yaml
+	apt-get install python3-pyscard python3-serial python3-cmd2 python3-pip python3-yaml
 	pip3 install pytlv