Added python3-flask to dependencies

Added python3-flask to dependencies

Thanks to LexBarringer!

README.md

@@ -5,8 +5,8 @@ A lightweight Python-based Web-GUI for Linux traffic control (tc) to set, view a
 ## Requirements
 
 - tested with ubuntu 16.04 LTS
-- netem is required
-    - install with `sudo apt-get install iproute`
+- netem tools & python3-flask is required
+    - install with `sudo apt-get install iproute python3-flask`
 - more information: https://calomel.org/network_loss_emulation.html
 
 ## Usage