Thai Getting USA tourist visa.

On the application form DS-160 there is a place for supporting documentation to be uploaded. What type of information goes here.  My GF and I left it blank because it said something that made me think this was not a place for bank book copies or work release letter.  I forget what it said?   But I am worried about this now because I expected a later location to upload these type of documents. She will be bringing these to her interview.. the schedule in BKK was out a month.  But I have read that  the approval has already been made on what you submitted and that any records you bring can not influence his decision.   OR is this for the K1 visa?   about 10 days away from knowing... nothing like having USA govt choose your romantic choices.

This site is good to preview the DS 160 questions but i cant find that upload area. 

Any reassurance will be appreciated..  

https://www.immihelp.com/visas/ds-160-usa-visa-form-guide.html