Rust 01-hello-world readme fixes

[paulreimer]

Improves, updates, and fixes outdated or missing steps in the rust hello-world README.

[paulreimer]

The following commits are (I believe) valid:

• 4bd7cae6def15a5e3fc6cb7d0782f2922665b450
• 183504c0c1f14ae504d81c361c960d7858333e8b
• 25931dd59bcd204df9673c44f38dcc9c53a41a07

However, I am still not able to follow the "dynamic" linking steps: I see the following error:

% LD_LIBRARY_PATH=lib64 ops run -c config.json main

 100% |████████████████████████████████████████|  [0s:0s]
panic: failed building manifest: stat /lib64/ld-linux-x86-64.so.2: no such file or directory

goroutine 1 [running]:
github.com/nanovms/ops/cmd.runCommandHandler(0xc000a19900, {0xc000a363f0, 0x1, 0x3})
        /Users/eyberg/go/src/github.com/nanovms/ops/cmd/cmd_run.go:62 +0x348
github.com/spf13/cobra.(*Command).execute(0xc000a19900, {0xc000a363c0, 0x3, 0x3})
        /Users/eyberg/go/pkg/mod/github.com/spf13/[email protected]/command.go:860 +0x5f8
github.com/spf13/cobra.(*Command).ExecuteC(0xc000923900)
        /Users/eyberg/go/pkg/mod/github.com/spf13/[email protected]/command.go:974 +0x3bc
github.com/spf13/cobra.(*Command).Execute(...)
        /Users/eyberg/go/pkg/mod/github.com/spf13/[email protected]/command.go:902
main.main()
        /Users/eyberg/go/src/github.com/nanovms/ops/ops.go:8 +0x1e

I could create a new issue for this, if that is preferred?