Update root LICENSE.txt to include chronoutil-derived MIT code

[alamb]

Describe the bug

• related to Release arrow-rs / parquet Major version 60.0.0 (August 2026) #9880
  @Xuanwo notes on the release thread for version 60 https://lists.apache.org/thread/r170ogy3ry3go1woz9mb9kdc1ysk1xgw:

The source archive includes chronoutil-derived MIT code in
arrow-array/src/delta.rs. The MIT license and attribution are
preserved, but the root LICENSE.txt does not identify this
component or point to arrow-array/LICENSE-MIT.

Please add that coverage to the root LICENSE.txt for the next
release. I am not blocking this release on this issue.

To Reproduce

See above

Expected behavior

Add the note in LICENSE.txt as suggested

Additional context

No response

[alamb]

I also added this to the list of required items for the next release

• Release arrow-rs / parquet Minor version 60.1.0 (September 2026) #10525