Add direct transfer contribution docs to global nav

What does this MR do and why?

Companion to: gitlab!152313 (merged), add groupimport and integrate development guidelines to global nav.

Screenshots, screen recordings, or links to review app

• Review app: https://eread-add-direct-transfer-contribution-docs-to-global-nav.docs.gitlab-review.app/ee/development/bulk_imports/contributing.html

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this merge request.