Update datasets loading script

Update olympiads-ref.py

Add data for asian pacific mathematics olympiad (APMO) (#2)

Add dataset loading script

add LFS support for pdf and word documents

edit README.md: add folder for download_script

updtae README.md: add instructions to add more data using pipeline.

add data for IMO, USA_TST, USA_TSTST, USAJMO, USAMO

add README

add git ignore

initial commit