Improve Windows Build & Usage Experience

[desert98]

1. just Tool Shell Compatibility

• Issue: Using just in PowerShell triggers errors (e.g., "Backtick could not be run because just could not find the shell").
• Fix: just works reliably in Bash (e.g., Git Bash).
• Suggestion: Document that Bash/Git Bash is recommended for just commands on Windows.

2. Rust Version Requirement

• Issue: smartdns@0.12.2 requires rustc 1.87.0+, but version upgrade isn’t emphasized in docs.
• Fix: Run rustup update stable to get the latest Rust.
• Suggestion: Add a note to run rustup update stable before building.

3. Command-Line Help Usage

• Issue: ./target/release/smartdns help treats "help" as a DNS query (errors with "proto error: no records found...").
• Fix: The correct command is ./target/release/smartdns --help (use --help flag).
• Suggestion: Document --help (not help) for CLI help in usage guides.

[mokeyish]

PRs are welcome