change the jenkins CI integration document and use `vela up` command

[barnettZQG]

https://kubevela.net/docs/case-studies/jenkins-cicd

This document working on vela core, there is no API server, so we will use vela up command to upgrade the application in the Deploy stage.

vela CLI must depend on the Kube API server.

[karnatisrinivas]

Can I take this up? /assign