DOC-3146: downgrade pagebreak_split_block lvl to Low.

Author: kemister85

modules/ROOT/pages/migration-from-7x.adoc

@@ -25,7 +25,7 @@ Any items marked **"High"** level require immediate attention during migration.
 
 |xref:pagebreak-split-block-default[pagebreak_split_block Default Value]
 |The default value changed from `false` to `true`, affecting how page breaks interact with block elements.
-|Medium
+|Low
 
 |xref:editor-selection-setcontent-deprecated[editor.selection.setContent] Deprecated
 |Method deprecated. Use `editor.insertContent` instead.