Update CHANGELOG

Author: rachelekm

CHANGELOG.md

@@ -51,6 +51,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Add Favorites page [#765](https://github.com/azavea/echo-locator/pull/765)
 - Add conditional school choice link [#775](https://github.com/azavea/echo-locator/pull/775)
 - Add client feedback copy updates [#793](https://github.com/azavea/echo-locator/pull/793)
+- Add Spanish and Mandarin translations [#807](https://github.com/azavea/echo-locator/pull/807)
 
 ### Changed