src: redirect-warnings to file, not path

Use `file` as name of the argument, as the CLI documentation does.

PR-URL: https://github.com/nodejs/node/pull/13120
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

src/node.cc

@@ -3620,8 +3620,8 @@ static void PrintHelp() {
          "  --no-warnings              silence all process warnings\n"
          "  --napi-modules             load N-API modules\n"
          "  --trace-warnings           show stack traces on process warnings\n"
-         "  --redirect-warnings=path\n"
-         "                             write warnings to path instead of\n"
+         "  --redirect-warnings=file\n"
+         "                             write warnings to file instead of\n"
          "                             stderr\n"
          "  --trace-sync-io            show stack trace when use of sync IO\n"
          "                             is detected after the first tick\n"