[SPARK-45257][CORE][FOLLOWUP] Correct the from version in migration g…

…uide

### What changes were proposed in this pull request?

Correct the from version in migration guide

### Why are the changes needed?

Address comments  apache@8d59997#r128053622

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

Review

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes apache#43072 from pan3793/SPARK-45257-followup.

Authored-by: Cheng Pan <chengpan@apache.org>
Signed-off-by: Kent Yao <yao@apache.org>

docs/core-migration-guide.md

@@ -22,7 +22,7 @@ license: |
 * Table of contents
 {:toc}
 
-## Upgrading from Core 3.4 to 4.0
+## Upgrading from Core 3.5 to 4.0
 
 - Since Spark 4.0, Spark will compress event logs. To restore the behavior before Spark 4.0, you can set `spark.eventLog.compress` to `false`.