Update docs upon changes to Bruno: env inheritance, multipart contentType, inherited headers

[mintlify]

Summary

Documents three user-facing changes merged in usebruno/bruno between 2026-09-07 and 2026-09-14.

Changes

• Environment inheritance (extends) — Added an "Environment inheritance" section to variables/environment-variables.mdx covering the parent selector, resolution/precedence, and the .bru / .yml file formats. Added a matching section to variables/global-environment-variables.mdx (upstream PR #9136).
• Per-part contentType on multipart bodies — Documented @contentType(<mime>) on multipart entries in bru-lang/tag-reference.mdx and added a contentType example plus preservation note under http.body multipart in opencollection-yaml/structure-reference.mdx (upstream PR #9155).
• Inherited Headers accordion — Added an "Inherited headers" section to send-requests/REST/req-header.mdx describing the new accordion, source navigation, and precedence rules (upstream PR #9129).

Context

Only latest (v4) docs were updated. Skipped:

• PR #9174 (git clone branch selection) — reverted in the same window.
• PRs #9225 / #9202 / #9206 (multi-select for examples in the sidebar) — sidebar UX improvements not currently covered by any page.
• PRs #9156, #9159, #9170, #9201, #9205, #9215, #9216, #9228 — bug fixes with no doc-visible surface change.

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Project	Status	Preview	Updated
bruno-docs-main	🟢 Ready	View Preview	Sep 14, 2026, 5:16 AM