update changelog

Author: SimenB

CHANGELOG.md

@@ -61,6 +61,8 @@
 
 ### Fixes
 
+* `[jest-util]` Install fix for `instanceof` as part of other globals into test
+  environments ([#5995](https://github.com/facebook/jest/pull/5995))
 * `[jest-jasmine2]` Install `sourcemap-support` into normal runtime to catch
   runtime errors ([#5945](https://github.com/facebook/jest/pull/5945))
 * `[jest-jasmine2]` Added assertion error handling inside `afterAll hook`