Update ftanf page verbiage

[victoriaatraft]

Description:
We've received feedback about the ftanf page. its outdated and suggests the transition from tdrs to tdp is still in progress. just a heads up that we need a ticket to track an update to this page.

From August 15 Release Notes:
We have relaxed TDP's data processing requirements to help ensure that the data in your files can still be processed even if these files have an invalid value for the update indicator. However, the TDP system expects the header update indicator to be set to "D" and if not, your error report will still include an error asking you to correct it. Read more about the header record and how to export complete data using fTANF.