Add ST3 tag for Modelines package

[Frizlab]

• I'm the package's author and/or maintainer.
• I have read the docs.
• I have tagged a release with a semver version number.
• My package repo has a description and a README describing what it's for and how to use it.
• My package doesn't add context menu entries. *
• My package doesn't add key bindings. **
• Any commands are available via the command palette.
• Preferences and keybindings (if any) are listed in the menu and the command palette, and open in split view.
• If my package is a syntax it doesn't also add a color scheme. ***
• I use .gitattributes to exclude files from the package.

This PR only adds the ST3 release series of the Modelines package which has been recently resurrected.