Delete README_BACKUP_3182.md

Delete README_BASE_3182.md

Delete README_REMOTE_3182.md

Delete README_LOCAL_3182.md

Update README.md

Update README.md

added precourse file

first commit

commit modifed changes in js-exercises-d1-kerenren, js-exercises-d2-kerenren

stuff about Chengdu

commit 2

Stuff about pandas

git intro class, intial commit