docs: update readme.md to match the output

[rrain7]

the output in README.md is

 :) cargo run
   Compiling init-operator v0.1.0 (/home/xuanwo/Code/apache/incubator-opendal/examples/rust/01-init-operator)
    Finished dev [unoptimized + debuginfo] target(s) in 0.38s
     Running `target/debug/init-operator`
operator from builder: Operator { accessor: S3Backend { core: S3Core { bucket: "example", endpoint: "https://s3.us-east-1.amazonaws.com/example", root: "/", .. } }, limit: 1000 }
operator from map: Operator { accessor: S3Backend { core: S3Core { bucket: "example", endpoint: "https://s3.us-east-1.amazonaws.com/example", root: "/", .. } }, limit: 1000 }

ref: lets-go

[suyanhanx]

Thanks!

[Xuanwo]

Thanks！