Well, the IBM DOC site is very much work in progress when it comes to Apptio. Searching for Apptio or Apptio Functions returns a list of pages, mostly related to Targetprocess.
Hopefully, this will work better by mid-April, when they say the migration will be complete. For now, it's certainly much better using the (outdated) PDF versions), @Varad Rajeev Muthal.