How to create table indexes in Paimon 1.2

### Search before asking

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

### Paimon version

paimon 1.2

### Compute Engine

Flink

### Minimal reproduce step

We plan to upgrade Paimon from 0.8 to 1.2，I know that if the index is a file index, I can use the 'with' attribute to specify it when creating the table. But I don't know how to create a table index for a table in Paimon 1.2，I have readed the paimon documentation，But it not give an daemon，anyone can provide help？

### What doesn't meet your expectations?

table index

### Anything else?

_No response_

### Are you willing to submit a PR?

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

Begin with the Paimon 1.2 documentation and the table-index behavior described in the issue; compare it with the file-index `with` attribute and the 0.8-to-1.2 upgrade context. Done means documenting the supported way to create table indexes, or clarifying that no such procedure exists.

Written by the indexing model from the issue text.