more spellchecking/rewording

Comments:

The concept of a "successor" (line 92) was confusing because it is not formally introduced until later (line 123). I just removed it for now, but maybe you can think of a better way to explain it.

I was a bit iffy on the standard deviation stuff. Where does the 560 files figure come from? What does it mean to "take the square root of 50% of the files" (line 111)? And I'm not sure that a standard deviation of 100 fake files means a reroll nets you 50 extra fake files. Doesn't it just mean that 68% of hosts have within 100 fake files of the average?