* docs(#2856): add release notes for 1.39.0-rc.6
Documents what's actually in rc.6 (= rc.5 content + version-bump only —
release/1.39.0 was not synced with main before the bump) plus the known
SDK publish failure (@gsd-build/sdk@1.39.0-rc.6 is missing from npm with
404 PUT error). Format mirrors RELEASE-v1.39.0-rc.5.md.
Closes#2856
* docs(#2856): drop SDK refs from rc.6 notes; tag git log fence
Per maintainer + CodeRabbit review:
- Strip the 'Known issue: split publish' section, the SDK pin Note, and
the @gsd-build/sdk follow-up bullet. SDK publish failure is a known
separate issue and shouldn't block the rc.6 docs.
- Add bash language tag to the git log fence (markdownlint MD040).
