Preparing release v1.4.0 (#32)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74841af..abb355a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,7 @@
 Releases
 ========
 
-v1.4.0 (unreleased)
+v1.4.0 (2019-11-04)
 ===================
 
 -   Add `AppendInto` function to more ergonomically build errors inside a