Update CHANGELOG to include #867

CHANGELOG.md

@@ -22,6 +22,7 @@
   rather checks the generated Ruby syntax for errors.
 * Support Rails 5.1 Erubi template handler.
 * Support Sprockets 3. Thanks [Sam Davies](https://github.com/samphilipd) and [Jeremy Venezia](https://github.com/jvenezia).
+* Allow `@` as tag's class name. Thanks [Joe Bartlett](https://github.com/redoPop).
 * Raise `Haml::InvalidAttributeNameError` when attribute name includes invalid characters. (Takashi Kokubun)
 * Drop dynamic quotes support and always escape `'` for `escape_html`/`escape_attrs` instead.
   Also, escaped results are slightly changed and always unified to the same characters. (Takashi Kokubun)