Set release date

drbrain · drbrain · commit a787b3d736fe · 2020-04-30T19:44:59.000-07:00
diff --git a/History.txt b/History.txt
@@ -1,4 +1,4 @@
-=== 4.0.0
+=== 4.0.0 / 2020-04-30
 
 Breaking changes:
 
