Example 02 schemas

[AlexMikhalev]

Inspired by a fresh example 01-init-operator I wrote a simple write-and-read-back example for:

• Scheme::S3
• Scheme::Sled
• Scheme::Redis
• Scheme::Memory & Scheme::Dashmap

[Xuanwo]

Thank you for submitting your PR! However, I would prefer not to delve into various schemes and their features at this early stage. Additionally, dedicating two chapters solely to initiating tasks does not seem like a productive use of time.

Instead, in chapter 02, I plan on introducing async and OpenDAL's read operation so that users can begin working on practical applications.

We will go back to different schemes after we have built simple working demos to show OpenDAL's power to switch between different services.

Thanks for your PR again!

[AlexMikhalev]

@Xuanwo looking forward to it. Maybe I can help with practical examples too - I am building a small app parsing markdown and storing tags in Dashmap or Redis.

[Xuanwo]

Thank you for the pull request. I have added a new example through #2541. I will now close this PR. Please inform me if you have any further questions.

Thanks again!