LuaDocs/Desc attributes spelling fixes

I have gone through the Desc attributes used during the LuaDocs generation and made some spelling, punctuation, and consistency fixes. If desired I would not mind going through the other Desc attributes as well.
I changed this to "the player" to be consistent with how MarkCompletedObject was described, I can change it to "this player" as used in the AddPrimary/SecondaryObjective if you want.