Finalize release notes for v8.18.4

Author: elasticsearchmachine

docs/reference/release-notes/8.18.4.asciidoc

@@ -1,8 +1,6 @@
 [[release-notes-8.18.4]]
 == {es} version 8.18.4
 
-coming[8.18.4]
-
 Also see <<breaking-changes-8.18,Breaking changes in 8.18>>.
 
 [[bug-8.18.4]]