[Doc]: example to set up the client to connect to an ob cluster

[ShiKaiWi]

Description

Some key parameters of the client are not clear enough for the first trial, e.g. sys_user_name, sys_password, full_user_name, param_url.

Shall we provide an example to explain these parameters and help the users set up the client to connect a self-hosted ob cluster?

Documentation links

I guess we can just put it in the README.md.

Additional context

Are there any special operations when creating the self-hosted ob cluster to enable access by table api?

[ShiKaiWi]

Here is a simple explanation in Chinese in the go SDK: https://github.com/oceanbase/obkv-table-client-go/wiki/%E5%88%9B%E5%BB%BAGo%E5%AE%A2%E6%88%B7%E7%AB%AF%E5%AE%9E%E4%BE%8B

@tisonkun For now, maybe you can have a try according to the line above. And I'll make an update on the README.md about it later.