document how to implement custom middleware to handle various errors

### Feature Request



|    Q        |   A
|------------ | ------
| New Feature | yes
| RFC         | yes/no
| BC Break    | yes/no

#### Summary
Based on this PR 
when we return a custom message when the paylod is invalid json 

https://github.com/dotkernel/api/pull/476#event-21235676283