[doc][improve] Add exception examples for transaction API

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### What issue do you find in Pulsar docs?

No exception examples for [transaction API docs](https://pulsar.apache.org/docs/next/txn-use/)

Thanks for raising this up! @BewareMyPower
Thanks for your technical guidance! @congbobo184 @liangyepianzhou

### What is your suggestion?

Add exception examples

### Any reference?

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!