A few small fixes to DigitalOcean Guide

[jslvtr]

• Avoid “simply”, “basically”, and similar words; first time learners (our readers) may not find it simple or basic :D
• We’re not offering students a $10 coupon, but rather an affiliate link. DigitalOcean gives them $10 if they sign up with our link, and we also get money when they spend money (but it doesn’t make it more expensive for them). It’s almost always a good idea to be upfront about this, otherwise if people out they may feel cheated.

[CristianoYL]

Very helpful!