Update installation.rst

Includes a command that fixes this issues

kivy#1052
kivy#1057

docs/source/installation.rst

@@ -23,6 +23,7 @@ Android on Ubuntu 18.04 (64bit)
     sudo apt update
     sudo apt install -y git zip unzip openjdk-8-jdk python3-pip autoconf libtool pkg-config zlib1g-dev libncurses5-dev libncursesw5-dev libtinfo5 cmake libffi-dev
     pip3 install --user --upgrade cython virtualenv  # the --user should be removed if you do this in a venv
+    python3 -m pip install --upgrade pip virtualenv
 
     # add the following line at the end of your ~/.bashrc file
     export PATH=$PATH:~/.local/bin/