See the Pluto Planet Guide (Book Edition), that is, the official documentation for how to design your own template packs.
Q: Why use planet.starter.html for the filename (and NOT just simple planet.html)?
A: By adding starter you can try other template packs (such as digest, hacker, top, etc.)
and the generated planet pages will NOT overwrite each other but will
live side-by-side in the same folder
(e.g. planet.digest.html, planet.hacker.html and so on) letting you try or serve
many styles / designs / themes.
Q: What's starter.txt good for?
A: The starter text file is the template pack(age) manifest (similar to package.json in the node.js world or gemspec in ruby)
listing all files (in plain text) that will get included.
The name of the file e.g. starter (without the .txt extension)
will get used as the name for the template option e.g. use -t starter or --template starter.
Send them along to the wwwmake Forum/Mailing List. Thanks!