Note about #770 in Haml 5 changes

This affects code like this:
https://github.com/sferik/rails_admin/blob/e0eb6ca714c9301b36efab9b43c6e38b55508db2/app/views/layouts/rails_admin/application.html.haml#L13

CHANGELOG.md

@@ -18,6 +18,7 @@
   to the source Haml file from which it was generated. Thanks [Alex Babkin](https://github.com/ababkin).
 * Fix #@foo and #$foo style interpolation that was not working in html_safe mode. (Akira Matsuda)
 * Add `haml_tag_if` to render a block, conditionally wrapped in another element (Matt Wildig)
+* Escape Ruby script interpolated in filters. (Matt Wildig)
 * The `haml` command's debug option (`-d`) no longer executes the Haml code, but
   rather checks the generated Ruby syntax for errors.
 * Support Rails 5.1 Erubi template handler.