chore: update `Iceberg` install docs

[comphead]

Which issue does this PR close?

Closes #.

Rationale for this change

Installed Iceberg using docs and my attempt has been failing on

Caused by: java.lang.ClassNotFoundException: org.apache.spark.sql.comet.execution.shuffle.CometShuffleManager

Presumably because of wrong separator for jars

What changes are included in this PR?

How are these changes tested?