v4.2.0
[SPARK-29052][DOCS][ML][PYTHON][CORE][R][SQL][SS] Create a Migration Guide tap in Spark documentation
[SPARK-54784][ML][DOCS] Document the security policy on ml models
[SPARK-24499][SQL][DOC] Split the page of sql-programming-guide.html to multiple separate pages
[SPARK-49378][DOCS][SS] Break apart the Structured Streaming Programming Guide