clarification of uploadfield in 29.06; minor typo/grammar fixes in 29.03 and 29.04

In section 06, uploadfield does not specify in what way it should be set: with some particular kind of value, a boolean, or what. I added clarification that it should be a boolean (after finding out the hard way).

In section 03, %b is presented in the day field, but %b is the abbreviated month. It should probably be %d for the numeric day-of-month number.

In section 04, added a very minor grammar fix.