Update install instructions to cover sequelize
Update install instructions to cover sequelize

We instruct people to run db migrations on inital setup. We should do
that!

Signed-off-by: Sheogorath <1c2647ce2ee8a4ec8e5c8b1b245ca38f94844bab@shivering-isles.com>

Yukaii/hackmd,hackmdio/hackmd,jackycute/HackMD,jackycute/HackMD,jackycute/HackMD,Yukaii/hackmd,Yukaii/hackmd,hackmdio/hackmd,hackmdio/hackmd