[vitormattos]

Summary

• Replace two links that pin the n8n README to the pre-cleanup commit a7b772cf579fcbd734810661f6e2104bd8444e6a with the post-cleanup immutable commit 4d6e2b8b5f9dbbd254b4cc00ec5875411fac06ed.
• Keep the stable13 documentation independent and retain the relative workflow link within the pinned README.

Scope and evidence

• Two RST files only: developer_manual/api/external-email-signers.rst and developer_manual/integration/index.rst.
• Verified both pinned revisions have identical Git blob SHAs for examples/n8n/libresign-external-signature.json (16d0db680104d7cd219a847a1a9514f846043e1e) and examples/n8n/test-workflow.mjs (fbfa800d6ebb696cd107e4cea5c2ad05f28289bc).
• Locally passed sphinx-build -n -W -b html for developer manuals on main, stable13, stable14 and stable15; inspected both rendered links on each branch.
• Passed node --test examples/n8n/test-workflow.mjs (12 tests), node --test tests/js/*.test.mjs (29 tests), and python -m unittest discover -s tests -v (44 tests).
• git diff --check passed. No application code, API, webhooks, example JSON or test files changed.

Review

• Builds and tests do not constitute runtime E2E homologation. Review published HTML and branch-specific CI before merge.
• No automatic merge requested.

Follow-up to #165, #166, #167 and #168.