Update README.md to clarify positional argument usage for notarytool keychain profile

build/README.md

@@ -40,8 +40,9 @@ This repo includes `build/macos/build_sign_notarize.sh` to automate:
   - Create a `notarytool` keychain profile (recommended) so you don’t have to pass secrets on the command line:
 
 ```bash
-xcrun notarytool store-credentials \
-  --keychain-profile "<profile-name>" \
+# NOTE: <profile-name> is a positional argument (not a flag).
+# Pick any name you want, e.g. "strawberry-notary".
+xcrun notarytool store-credentials "<profile-name>" \
   --apple-id "<your-apple-id>" \
   --team-id "<TEAMID>" \
   --password "<app-specific-password>"