[docs](schema-change) Refine schema change rlated docs

[TangSiyang2001]

Versions

• [x] dev
• [x] 3.0
• [x] 2.1
• [ ] 2.0

Languages

• [x] Chinese
• [x] English

[KassieZ]

please also update 2.1/3.0

[TangSiyang2001]

run buildall