fix readme.md
fix readme.md

in 5.2.2 fast mode
'cd /data/projects/fate/examples/toy_example/' should be '/data/projects/fate/examples/min_test_task/'

Signed-off-by: Yao544303 <1aee0a8db8b479dff54964adda6a80b330df09d5@gmail.com>

FederatedAI/FATE,FederatedAI/FATE,FederatedAI/FATE