Suggestion: Add more use cases to Web3j documentation

[zhoujingweb3]

Issue_title

Web3j documentation could benefit from more practical use cases.

Issue_description

Web3j is a powerful tool, but for newcomers, its documentation can be quite complex. Sometimes, developers only need to use a specific feature of Web3j, and they may struggle to find clear examples.

To address this, I have created a GitHub repository: web3j-eth-sample, which provides various use cases and sample code for Web3j.

The repository includes step-by-step guides and working examples, making it easier for developers to get started with Web3j without having to go through extensive documentation.

I believe adding more practical examples like these to the official documentation would greatly improve the developer experience.

Issue_context

I would love to hear your thoughts on this! If you find this idea useful, I’d be happy to collaborate on integrating some of these examples into the official documentation or Web3j's learning resources.

Let me know if there's any way I can contribute!