IMPALA-14705: [DOCS] Update DML docs for Iceberg DELETE and UPDATE su…

[gbisatis24]

Summary:

This PR adds DELETE and UPDATE DML support for Iceberg Tables.

What changed:

Added the Iceberg support in docs/topics/impala_dml.xml for DELETE and UPDATE Statements.

Tests Performed:

Verified the documentation changes locally by running:

make all

This completed successfully and generated:

./build-doc.sh xhtml build/plain-html/ impala_html.ditaval gen-plain-html.log
./build-doc.sh html5 build/asf-site-html/ impala_html.ditaval gen-asf-site-html.log --pretty
./build-doc.sh pdf build/ impala_pdf.ditaval gen-pdf.log

Additionally verified:

1. ./pre-commit.sh completed successfully with no errors.
2. xmllint --noout docs/topics/impala_dml.xml completed successfully with no output.
3. git diff docs/topics/impala_dml.xml confirmed that the expected documentation changes were present.

[jasonmfehr]

Hi @gbisatis24, we use Gerrit for code changes to Impala instead of Github PRs. Please close this PR and see https://cwiki.apache.org/confluence/display/IMPALA/Contributing+to+Impala for details on how to submit this change via Gerrit.