Added entry into changelog.md

Author: alex-petrov-vt

CHANGELOG.md

@@ -10,7 +10,7 @@ Note that this project **does not** adhere to [Semantic Versioning](http://semve
 ## [Unreleased]
 
 ### Added
-
+- We improved responsiveness of general fields specification dialog window [#6643](https://github.com/JabRef/jabref/issues/6604)
 - We added support for importing ris file and load DOI [#6530](https://github.com/JabRef/jabref/issues/6530)
 - We added the Library properties to a context menu on the library tabs [#6485](https://github.com/JabRef/jabref/issues/6485)
 - We added a new field in the preferences in 'BibTeX key generator' for unwanted characters that can be user-specified. [#6295](https://github.com/JabRef/jabref/issues/6295)