Add a user guide for features in Project 2

[mohamed-elzeni]

This adds a user guide that provides an outline of how to use and user test the new features added to NodeBB by the Logic Lords team. It also includes a description of the added automated tests for these features and where to find them.

Resolves #50.

[coveralls]

Pull Request Test Coverage Report for Build 11429021926

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.002%) to 82.677%

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Files with Coverage Reduction	New Missed Lines	%
src/notifications.js	1	78.62%

Totals
Change from base Build 11428788904:	0.002%
Covered Lines:	22363
Relevant Lines:	25627

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💛 - Coveralls

[tatougueye]

Looks good!