book: update swiftc-and-cargo to use new subcommand

book/src/building/swiftc-and-cargo/README.md

@@ -163,9 +163,7 @@ fn main() {
 #!/bin/bash
 set -e
 
-# The swift-bridge CLI does not exist yet. Open an issue if you need to use
-# this approach and I'll happily whip up the CLI.
-swift-bridge -f src/lib.rs > generated
+swift-bridge-cli parse-bridges <package name> src/lib.rs
 
 swiftc -emit-library -static -module-name my_swift -import-objc-header bridging-header.h \
   lib.swift ./generated/swift-and-rust/swift-and-rust.swift