bbgo_origin/doc/release/v1.21.0.md

Fixes

• Fixed back-test concurrent read/write map issue
• Fixed back-test go routine initialization
• Fixed trade notification format - remove trade trailing zero digits
• Fixed dockerfile
• Fixed back-test kline sync issue

Refactoring

• Refactored and fixed depth buffer

Strategy

• Added rebalance strategy

Features

• Added prometheus metrics support
• Added kucoin exchange support
• Added bookTicker support to binance, okex, ftx
• Integrated net asset value recording table in db