Fix macOS files description

Author: hebasto

src/qt/README.md

@@ -64,8 +64,8 @@ Represents the view to a single wallet.
 * `callback.h`
 * `guiconstants.h`: UI colors, app name, etc
 * `guiutil.h`: several helper functions
-* `macdockiconhandler.(h/cpp)`
-* `macdockiconhandler.(h/cpp)`: display notifications in macOS
+* `macdockiconhandler.(h/mm)`: macOS dock icon handler
+* `macnotificationhandler.(h/mm)`: display notifications in macOS
 
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