Unclear documentation on employee mode

[nus-se-pr-bot]

In user guide, instructions are given on how to log in to admin mode. But, if i'm not in admin mode, am I in employee mode? If i'm in employee mode, which employee am I? There should be documentation that introduces working in employee mode right before the employee commands are listed in section 3.3.

_{[original: nus-cs2103-AY1718S2/pe-round1#633]}

Issue created by: @a-shakra