Update db docs.
Update db docs.

Sunzhifeng/peewee,coreos/peewee,wenxer/peewee,coreos/peewee,teserak/peewee,d1hotpep/peewee,ghukill/peewee,jarrahwu/peewee,coleifer/peewee,py4a/peewee,d1hotpep/peewee,Dipsomaniac/peewee,ronyb29/peewee,new-xiaji/peewee,zhang625272514/peewee,fuzeman/peewee,bopo/peewee,coreos/peewee,bopo/peewee,lez/peewee,wenxer/peewee,jarrahwu/peewee,coleifer/peewee,stas/peewee,Sunzhifeng/peewee,coleifer/peewee,mackjoner/peewee,new-xiaji/peewee,new-xiaji/peewee,jnovinger/peewee,softside/peewee,jarrahwu/peewee,bopo/peewee,zhang625272514/peewee,zhang625272514/peewee,Dipsomaniac/peewee,Sunzhifeng/peewee,jnovinger/peewee,Dipsomaniac/peewee,fuzeman/peewee