Remove instructions about installing from APT.
Partially fixes
Installation
============
-If you're running on Ubuntu Xenial or greater::
-
- sudo apt install python-pylxd lxd
-
-Otherwise you can track LXD development on other Ubuntu releases::
-
- sudo add-apt-repository ppa:ubuntu-lxc/lxd-git-master && sudo apt update
- sudo apt install lxd
-
-Or install pylxd using pip::
+Install pylxd using pip::
pip install pylxd
