Update README.md

Merge pull request #11 from rwang5688/make-upserts.py-and-upserts.sql-work

make upserts.py and upserts.sql work

add upserts.sql

make upserts.py and upserts.sql work

Merge pull request #10 from rwang5688/add-upserts.py-baseline

add upserts.py baseline

Merge pull request #9 from rwang5688/add-date-partitions

add date partitions

Merge pull request #8 from rwang5688/align-code-with-original-source-for-easier-comparison-afterwards

align code with original source for comparesion

Merge pull request #7 from rwang5688/make-create-default-superstore.sql-work

make create-default-superstore.sql work

Merge pull request #6 from rwang5688/add-create-table-athena-query

add create table query for athena