changelog: don't mark additional module name in the log as breaking

Remove the "breaking change" mark, as it's highly unlikely that it will
break any log parser.

Follow-up #3211

NO_DOC=changelog
NO_TEST=changelog

changelogs/unreleased/gh-3211-per-module-log_level.md

 ## feature/core
 
-* **[Breaking change]** Now the log message contains the name of a module from
-  which the logging function was called (gh-3211).
+* Now the log message contains the name of a Lua module from which the logging
+  function was called (gh-3211).
 
 * Now the log level can be set for specific modules using `log.cfg{modules = {...}}`
   or `box.cfg{log_modules = {...}}` (gh-3211).