docs: Update release README examples to 55.2.0 and add SVN commands

[comphead]

Which issue does this PR close?

• Related to Release DataFusion 55.2.0 (patch) Release (Oct 2026) #25758.

Rationale for this change

The release README used 50.x examples and had no commands to check, download or unpack the artifacts in SVN.

What changes are included in this PR?

In dev/release/README.md:

• Use 55.2.0 in the examples.
• Step 2: add the sed and cargo update --workspace commands for the version and lockfile.
• Add svn ls checks after the uploads, and svn export plus tar xzf commands for the release tarball.
• Step 13: keep the last major release (55.0.0 in the example) and the releases after it in the release SVN, with a short loop that prints the svn delete commands for the other releases.

What is the testing strategy for this PR?

Docs only. The sed commands reproduce the Cargo.toml and docs changes of the 55.2.0 release PR (#26037). The loop was run in bash, zsh and sh against a local SVN repository.

Are there any user-facing changes?

No.

[timsaucer]

One minor requested change. Thanks for updating the documentation!

[timsaucer]

In general there should only be one prior release if we've been deleting them. I often copy+paste this line so I'd prefer it to only show one.

[comphead]

Thanks @timsaucer for the review, not sure I'm following, appreciate if you elaborate . I thought we need to remove old prior release with fixes.

Now I can see in svn no last major release, not sure if this is expected

[comphead]

https://dist.apache.org/repos/dist/release/datafusion/

[timsaucer]

The PR is changing the line

svn delete -m "delete old DataFusion release" https://dist.apache.org/repos/dist/release/datafusion/datafusion-50.0.0

to

svn delete -m "delete old DataFusion release" \
  https://dist.apache.org/repos/dist/release/datafusion/datafusion-54.0.0 \
  https://dist.apache.org/repos/dist/release/datafusion/datafusion-54.1.0

When I've run this command in the past it was helpful to copy & paste this line and edit the version number. I'm guessing when you went through this you needed to delete both 54.0.0 and 54.1.0?

I was just suggesting this be

svn delete -m "delete old DataFusion release" https://dist.apache.org/repos/dist/release/datafusion/datafusion-54.1.0

[comphead]

Ic, it was an example, let me come up with script then so it would work for any release

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.73%. Comparing base (f9b7f34) to head (a1101e1).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #26119      +/-   ##
==========================================
- Coverage   82.73%   82.73%   -0.01%     
==========================================
  Files        1147     1147              
  Lines      449459   449540      +81     
  Branches   449459   449540      +81     
==========================================
+ Hits       371864   371918      +54     
- Misses      54936    54946      +10     
- Partials    22659    22676      +17     

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[comphead]

Thanks @timsaucer for the review, I added a small bash command for deletes which prints the svn delete and once the release manager verifies they can run it