[DOCS] Removes breaking change (#31376)

Author: lcawl

docs/reference/release-notes/6.3.asciidoc

@@ -1,5 +1,5 @@
 [[release-notes-6.3.0]]
-== 6.3.0 Release Notes
+== {es} version 6.3.0
 
 Also see <<breaking-changes-6.3>>.
 
@@ -31,10 +31,6 @@ Security::
 with an SPI based extension mechanism that is installed and built as an
 elasticsearch plugin.
 
-Task Management::
-* Remove metadata customs that can break serialization {pull}30945[#30945] (issues: {issue}30731[#30731], {issue}30857[#30857])
-
-
 [[breaking-java-6.3.0]]
 [float]
 === Breaking Java changes