Version Control (Git and Github)
Git
git is a distributed version control system that keeps track of the changes between plaintext source files. It can be used for collaboration or for managing and keeping track of workflows for individuals. While primarily intended for software source code, git works with any plaintext files, and so can also be used for authoring of other kinds.
Git - The Simple Guide (PDF) (WEB)
Git Tutorials and Training - Atlassian
GitHub
GitHub is a platform that allows for users to keep copies of their open source, plaintext repositories online, in a single centralized location. It also adds a social interaction layer to the process of managing version-controlled source files.
Keeping GitHub forks up to date with upstream source
Keeping your forked repo synced with the upstream source - Nitin Venkatesh