[api] document API specification by openapi
[api] document API specification by openapi

Closes: #9468

aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,libra/libra,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,aptos-labs/aptos-core,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra