doc: correct npm@6.4.0 release date in changelog (#53)

charmander · zkat · commit 767699b6829b · 2018-08-20T16:17:49.000-07:00
PR-URL: #53 Credit: @charmander Reviewed-By: @zkat
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## v6.4.0 (2018-09-08):
+## v6.4.0 (2018-08-09):
 
 ### NEW FEATURES
 
