Using GitHub via a browser, I am failing to create the Releases assets source code zip and tar.gz files that contain my src/filename.php files. Syncing to Packagist appears to work OK, but Composer then not unexpectedly fails to load my source files into the usual vendor/packagename/src/ subdirectory.
I have tried loading the source files themselves into the main part of the repository into subdirectory /src using Add file. I have also added a zipped and a tarballed version into Releases file upload.
GitHub documentation is somewhat light on this, so could someone kindly explain exactly what I am doing wrong.