test(helm): expect Recommended minimal install (26.08) in README check

[kheiss-uwzoo]

Summary

• Updates the Helm README unit-test marker from Recommended minimal install (26.05) to (26.08) so it matches the section renamed in docs: rebrand main docs to 26.08 for RC GitHub Pages QA #2430.
• Unblocks the failing Retriever unit / Docker README check Julio flagged.

Test plan

• pytest nemo_retriever/tests/test_helm_optional_nims_disabled_by_default.py::OptionalNimsDefaultDisabledTests::test_readme_minimal_install_no_longer_disables_parse_or_omni
• CI unit tests green on this PR

[kheiss-uwzoo]

Follow-up for Julio: #2430 merged before this README unit-test marker update landed. This PR is the one-line test fix for Recommended minimal install (26.08).

[greptile-apps]

Greptile Summary

This PR synchronizes a Helm README regression test with the minimal-install section renamed for release 26.08.

• Updates the expected README heading marker from 26.05 to 26.08.
• Updates the corresponding test documentation and failure message.

Confidence Score: 5/5

The PR appears safe to merge with no actionable defects identified.

The updated marker uniquely matches the current Helm README heading, and the existing test continues to inspect the intended minimal-install recipe.

Important Files Changed

Filename	Overview
nemo_retriever/tests/test_helm_optional_nims_disabled_by_default.py	Correctly updates the stale README section marker and related explanatory text to match the unique 26.08 heading.

_{Reviews (1): Last reviewed commit: "test(helm): expect Recommended minimal i..." | Re-trigger Greptile}