Remove release note (again?)

This was previously removed, but somehow snuck back in.

Previous discussion: #1246 (comment)
Previous revert commit: d6a551a

Author: mchowning

RELEASE-NOTES.txt

@@ -8,7 +8,6 @@
 * Adding a block from the post title now shows the add block here indicator.
 * Deselect post title any time a block is added
 * Fix loss of center alignment in image captions on Android
-* Fix merging of empty paragraph blocks when added from a post's title
 
 1.9.0
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