[SPARK-52324][INFRA] Move Spark docs to the release directory

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

The docs of old Spark versions are served from the Apache release directory instead of the spark-website. We need to move Spark docs to the Apache release directory when finalizing the release.

This PR updates the release scripts to do so.

### Why are the changes needed?

release process

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

no

### How was this patch tested?

No, we will test it when finalizing Spark 3.5.6

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

no

Closes apache#51026 from cloud-fan/release.

Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>

Author: cloud-fan

dev/create-release/release-build.sh

@@ -158,10 +158,14 @@ if [[ "$1" == "finalize" ]]; then
   git push origin HEAD:asf-site
   cd ..
   rm -rf spark-website
-  svn rm --username $ASF_USERNAME --password "$ASF_PASSWORD" -m"Remove RC artifacts" --no-auth-cache \
-    "$RELEASE_STAGING_LOCATION/$RELEASE_TAG-docs"
   echo "docs uploaded"
 
+  # Moves the docs from dev directory to release directory.
+  echo "Moving Spark docs to the release directory"
+  svn mv --username "$ASF_USERNAME" --password "$ASF_PASSWORD" -m"Apache Spark $RELEASE_VERSION" \
+    --no-auth-cache "$RELEASE_STAGING_LOCATION/$RELEASE_TAG-docs/_site" "$RELEASE_LOCATION/docs/$RELEASE_VERSION"
+  echo "Spark docs moved"
+
   # Moves the binaries from dev directory to release directory.
   echo "Moving Spark binaries to the release directory"
   svn mv --username "$ASF_USERNAME" --password "$ASF_PASSWORD" -m"Apache Spark $RELEASE_VERSION" \