message: Add shell prompt ("$") to command
diff: @@ -60,7 +60,7 @@ If it gives the error "Command not found", then the package has not been
  installed yet. To install if for the first time, run:
  <pre>$ sudo apt-get install python3-pip # for Python 3.n
  -sudo apt-get install python-pip # for Python 2.7</pre>
  +$ sudo apt-get install python-pip # for Python 2.7</pre>
  You can find more help on installing and upgrading pip in
  [the Raspberry Pi documentation](https://www.raspberrypi.org/documentation/linux/software/python.md).
  