* [V3 Docs] drop ffmpeg from CentOS install guide
* [V3 Install Docs] move all to Python 3.6
* Update the toctree
* Needed a blank line
* drop a .6 that wasn't needed
* Documentation extras
Added links to each distro's user add functions
Added systemd service guide
Added --user operator to pip install commands
* Update autostart_systemd.rst
Added no-prompt flag
* typo fix
* update docs with up to date reqs (remove old) and reccommend venv usage
* remove youtube_dl from reqs
* adding the mac doc update after verifying correctness
* venv installation required for py3.5 ...
* remove venv stuff, that can be handled on a unified page in a later PR