fixup! Update README with info about changes to version 5

Author: schtibe

README.md

@@ -1406,7 +1406,7 @@ formatters:
 
 ### Version 5.x.x Breaking Changes
 
-The fields `exc_text` and `stack_info` were removed from the message in JSON formatter. Instead they were added to the record so that they can be configured via the `fmt` field in the logging configuration.
+Previously, the fields `exc_text` and `stack_info` were always added to the log message if they existed. This behavior is slightly changed: instead of adding them to the message in any case, they were added to the record so that they can be configured via the `fmt` field in the logging configuration as described in [#case-10-add-stack-traces-to-log-records].
 
 ### Version 4.x.x Breaking Changes