Add user documentation

[ananyo2012]

Moving from #43 here are the few points we should add in the junction user documentation to make life of reviewers/admins easier

How tos

• Set up a conference
• Add reviewers for a conference
• Assign Section reviewers
• Private Comments
• Reviewers only collaboration

Features

One liner/small writeup about existing features.

Setup

How to setup third party packages like django-allauth (links to existsing one is also fine)
setting up special settings variables.

[ananyo2012]

@pradyunsg Is the Milestone only meant to improve developer documentation and not the user functionalities ?

[pradyunsg]

Yea, development-related stuff would be what we put in the milestone -- I don't think we should mix that with user-facing stuff.

A good metric would be "does this have any user-facing changes" -- yes? don't put it in the milestone. no? maybe put it in the milestone.