fix(trogonstack-diataxis): use README.md as navigation root instead of index.md

[yordis]

Summary

Fixup commit to correct the release-please component scope. The original PR #19 was merged with scope fix(diataxis) instead of fix(trogonstack-diataxis), so release-please did not pick it up for the correct package.

Test plan

• Verify release-please creates a release PR for trogonstack-diataxis after merge

[cursor]

PR Summary

Low Risk
No functional changes are introduced; only release metadata/commit scoping is affected.

Overview
No repository content changes are included in this PR (diff is empty), so behavior and documentation remain unchanged. The only effective change is the conventional-commit scope/title intended to make release-please cut a release for trogonstack-diataxis.

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