[Suggestion] Description of different "code" in MilvusException

[sharathts14]

Is there anything that's missing or inappropriate in the docs? Please describe.
There are no references to different "code" in MilvusExceptions. If we want to build custom application on top of this, it would be hard to raise appropriate errors without the reference code

Describe your suggestion
Add a section to show description of all the "code" in MilvusException

Additional reference
Provide any other reference docs or websites about your request.