clarify we mean PyPI

Signed-off-by: William Woodruff <[email protected]>

Author: woodruffw

README.md

@@ -8,7 +8,7 @@ A GitHub Action that uses [`sigstore-python`](https://github.com/sigstore/sigsto
 to generate Sigstore signatures.
 
 > [!IMPORTANT]
-> Are you publishing a package? If so, you **do not need this action**:
+> Are you publishing a package to PyPI? If so, you **do not need this action**:
 > [pypa/gh-action-pypi-publish](https://github.com/pypa/gh-action-pypi-publish)
 > will handle signing for you!