message: Add CLI help text for patch-in-config
diff: @@ -45,6 +45,7 @@ Available unstable (nightly-only) flags:
  -Z terminal-width -- Provide a terminal width to rustc for error truncation
  -Z namespaced-features -- Allow features with `dep:` prefix
  -Z weak-dep-features -- Allow `dep_name?/feature` feature syntax
  + -Z patch-in-config -- Allow `[patch]` sections in .cargo/config.toml files
  Run with 'cargo -Z [FLAG] [SUBCOMMAND]'"
  );
  