feat: support ETA raw blocks

Author: dangh

README.md

@@ -14,6 +14,7 @@ References
 - [ERB Documentation](https://ruby-doc.org/stdlib-2.5.1/libdoc/erb/rdoc/ERB.html)
 - [EJS Documentation](http://ejs.co/#docs)
 - [ETLua Documentation](https://github.com/leafo/etlua)
+- [ETA Documentation](https://eta.js.org/docs)
 
 [ci]: https://img.shields.io/github/actions/workflow/status/tree-sitter/tree-sitter-embedded-template/ci.yml?logo=github&label=CI
 [discord]: https://img.shields.io/discord/1063097320771698699?logo=discord&label=discord

grammar.js

@@ -26,7 +26,7 @@ module.exports = grammar({
     content: _ => prec.right(repeat1(choice(/[^<]+|</, '<%%'))),
 
     directive: $ => seq(
-      choice('<%', '<%_', '<%|'),
+      choice('<%', '<%_', '<%|', '<%~'),
       optional($.code),
       choice('%>', '-%>', '_%>'),
     ),