Update changelog.txt

Author: b-g

changelog.txt

@@ -16,6 +16,10 @@ Improvements:
   * 270D better fingers of drawing hand by Daniel Utz
   * 1F383 removed unnecessary points by @yukal #555
   * font/README.md: easy font usage via jsdelivr.com by @jjb #570
+  * Fixing Japanese emoji and correcting legibility issues: 1F21A 🈚,
+    1F22F 🈯, 1F23A 🈺, 1F201 🈁, 1F202 🈂, 1F232 🈲, 1F233 🈳, 1F234 🈴,
+    1F235 🈵, 1F236 🈶, 1F237 🈷, 1F238 🈸, 1F239 🈹, 1F250 🉐, 1F251 🉑,
+    3299 ㊙, 3297 ㊗ #609 by @cemoon95
 
 Fix:
   * Updates flag sequences of non rendering extras-openmoji/flags by @SoSeDiK #600