Quote from MikkOkay, now that we've beaten embeds.xml to death, the other half should be properly addressed:
The reason why we have e.g. AceConfig-3.0/AceConfig.3.0.xml is because we want to be free to add more .lua files to the directory without having people's addons stop working.
If people manually list .lua files in their TOCs, we can't do that. But if they point at the .xml file, we can just include more files to load from there.
So... don't list library contents in your toc files. List the .xml file.