`Guides/Tablet_purchase` is very out of date.

This wiki page is quite out-of-date and is full of information that's no longer useful, 

Potentially revamp it using https://docs.google.com/spreadsheets/d/1DYVfiSpQqdpa4sWWYUALPmliOIuGyKog7B7LJJdmlhE/edit?gid=2077726645#gid=2077726645 and similar resources, and remove mentions of the osu!tablet (No real reason to still have that there)