Add blueprint to HTML Builders section (#613)

README.md

@@ -285,6 +285,7 @@ described in [RFC 8032]
  * [Ultimate GTK4 Crystal Guide](https://ultimate-gtk4-crystal-guide.geopjr.dev/) - Learn how to create premium GTK4 apps in Crystal
 
 ## HTML Builders
+ * [blueprint](https://github.com/gunbolt/blueprint) - Write reusable and testable HTML templates in plain Crystal
  * [form_builder.cr](https://github.com/westonganger/form_builder.cr) - Dead simple HTML form builder for Crystal with built-in support for many popular UI libraries such as Bootstrap
 
 ## HTML/XML Parsing