Add ytt syntax

[Vasfed]

• [x] I'm the package's author and/or maintainer.
• [x] I have have read the docs.
• [x] I have tagged a release with a semver version number.
• [x] My package repo has a description and a README describing what it's for and how to use it.
• [x] My package doesn't add context menu entries. *
• [x] My package doesn't add key bindings. **
• [x] Any commands are available via the command palette.
• [x] Preferences and keybindings (if any) are listed in the menu and the command palette, and open in split view.
• [x] If my package is a syntax it doesn't also add a color scheme. ***
• [x] If my package is a syntax it is named after the language it supports (without suffixes like "syntax" or "highlighting").
• [x] I use .gitattributes to exclude files from the package: images, test files, sublime-project/workspace.

My package is language syntax for Carvel's ytt

There are no packages like it in Package Control.