update changelog to v2.20.4 backport

CHANGELOG.md

@@ -41,13 +41,18 @@ _Breaking developer changes, which may affect downstream projects or sites that
 
 # Unreleased
 
-#### :bug: Bugfixes
-* Fix rendering of HTML content in KeepRight and ImproveOSM issues ([#8928])
-* Fix "local storage is exceeded" error message showing up multiple times ([#8930])
 #### :hammer: Development
 * Switch build system to [esbuild](https://esbuild.github.io/) for much faster builds ([#8774], thanks [@ mbrzakovic] and [@bhousel])
 
 [#8774]: https://github.com/openstreetmap/iD/pull/8774
+
+# 2.20.4
+##### 2022-Feb-03
+
+#### :bug: Bugfixes
+* Fix rendering of HTML content in KeepRight and ImproveOSM issues ([#8928])
+* Fix "local storage is exceeded" error message showing up multiple times ([#8930])
+
 [#8928]: https://github.com/openstreetmap/iD/pull/8928
 [#8930]: https://github.com/openstreetmap/iD/pull/8930