Just read through the download myself and I couldn't find any references to any additives at all.
A little flow enhancer or washing up liquid will help the washes or very diluted paint to go into the areas you want it.To be honest it would be a very good habit for you to take up and I don't think you will be looking back once you start. I use my flow enhancer in an old ink bottle with a dropper fitting. THis makes it far easier to add to mixes.

