Update changelog

Author: ehmicky

CHANGELOG.md

@@ -1,3 +1,19 @@
+# 6.0.0
+
+## Breaking changes
+
+- Previously, if the [`props`](README.md#-props) option was `false`, nested
+  errors
+  ([`error.cause`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/cause)
+  and
+  [`error.errors`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/AggregateError/errors))
+  were not printed. To achieve the same behavior, the
+  [`cause`](README.md#-cause) option must now be set to `false`.
+
+## Features
+
+- Nested errors are now printed on their own, which result in a prettier output.
+
 # 5.3.0
 
 ## Features