Updated RELEASE_NOTES.

RELEASE_NOTES.md

@@ -2,6 +2,8 @@
 
 ## 2.60
 
+New command-line option `export_csv`, that exports user data in a format suitable to be imported into Mastodon (specifically, `blocked_accounts.csv`, `bookmarks.csv`, `following_accounts.csv` and `lists.csv`).
+
 Fixed a bug in argument parsing regarding some special characters (contributed by ndagestad).
 
 ## 2.59