MERN Stack Login Methods (Hacktoberfest 2019)

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I want to create a project using MERN Stack, which has most of the famous login authentication systems.

I want to add more such implementations for instagram.

Client side implementation of these login methods (for api take a look at docs-for-api.md file)

Hactoberfest is a great time for performing such tasks with open source contributors.

I welcome everyone who can contribute here.

- Tasks:

- Documentation about this project
- React Client implentation for login 
- Adding more and more login systems

Note: Do not add keys while pull request