add README: provenance (quentinll originals) + decompress

add cube_single_expert.tar.zst -- original le-wm (source quentinll/lewm-cube)

add reacher.tar.zst -- original le-wm (source quentinll/lewm-reacher)

add pusht_expert_train.h5.zst -- original le-wm (source quentinll/lewm-pusht)

add tworoom.tar.zst -- original le-wm (source quentinll/lewm-tworooms)

initial commit