Add Changelog entry

Author: pirj

Changelog.md

@@ -10,6 +10,8 @@ Enhancements:
 Bug fixes:
 
 * Ensure bisect communication uses consistent encoding. (Mike Jarema, #2852)
+* Fix exception presenter when the root cause exception has nil backtrace.
+  (Zinovyev Ivan, #2903)
 
 ### 3.10.1 / 2020-12-27
 [Full Changelog](http://github.com/rspec/rspec-core/compare/v3.10.0...v3.10.1)