Added Vash Syntax Definitions

Hello!
Just made a syntax definition for the [Vash](https://github.com/kirbysayshi/vash) template engine. Plan on making snippets later on, but figured I'd start with this first!

Hopefully [this](https://github.com/theoperatore/VashSyntaxDefinition) gets accepted as a package!

Cheers,

Alex Petersen