Update release notes for PR #18609

Author: Giorgio Ruscigno

RELEASE-NOTES.txt

@@ -9,6 +9,7 @@
 * [*] Block Editor: Gallery block: Fix broken "Link To" settings and add "Image Size" settings [https://github.com/wordpress-mobile/gutenberg-mobile/pull/4841]
 * [*] Block Editor: Unsupported Block Editor: Prevent WordPress.com tour banner from displaying. [https://github.com/wordpress-mobile/gutenberg-mobile/pull/4820]
 * [*] Widgets: we fixed an issue where text appeared flipped in rtl languages [#18567]
+* [*] Posts list: we fixed an issue where the create button was not shown on iPad in split screen [#18609]
 
 19.8
 -----