Fix the Actual Resolution/Aspect ratio column order in res.md

[th0rgall]

The aspect ratio of iPhones with an 9 : 19.5 aspect ratio were shown under the "Actual resolution" column header; and all their actual resolutions were under the "Aspect ratio" header. This reverses the column <td>s to fix this.

[Brett-Best]

@ebelinski any chance this can be merged?

[NintendoManiac64]

@th0rgall Would it be too rude to throw in a quick fix for the early iPhone aspect ratios as well? They're listed as 3 : 4 but the math for their resolutions should instead be 2 : 3 (see also #76)