Update README.md

add support custom type Nullfloat64 (#1450)

fix bug when query map condtion with no quote (#1449)

Don't warn when bool column default is 1 but not true (#1447)

Fix sync2 with custom table name (#1445)

fix bug when update with setexpr (#1446)

add tidb tests on drone ci (#1444)

improve sync2 (#1443)

Fix wrong dbmetas (#1442)

Fix default value parse bugs (#1437)

fix arg conversion (#1441)

upgrade core (#1440)

add tests (#1439)

add go1.13 tests on drone (#1416)

Fix bug on insert where (#1436)