[release-branch.go1.27] write go 1.27 release notes

[gdams]

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[Copilot]

Pull request overview

Adds Microsoft build of Go 1.27 release notes content, focusing on the systemcrypto configuration change (no longer a GOEXPERIMENT), new FIPS 140 runtime knobs, backend/platform support updates, and newly backend-implemented ML-DSA parameter sets.

Changes:

• Document systemcrypto configuration changes (including MS_GO_NOSYSTEMCRYPTO=1 and removal of related GOEXPERIMENT values).
• Document new/updated FIPS 140 behaviors (GODEBUG=fips140=only and GODEBUG=fips140=off semantics).
• Document backend updates (OpenSSL cgo-less default support, FreeBSD support) and ML-DSA backend coverage.

Show a summary per file

File	Description
docs/go1.27.md	Adds Go 1.27 release notes entries for systemcrypto, FIPS 140 behavior, backend support, and ML-DSA parameter sets.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 2
• Review effort level: Low

[dagood]

The Configuration section, particularly first paragraph, was a bit of a wall of text, but instead of leaving a comment I decided to work with Copilot to rewrite things and pushed that up in a new commit. Feel free to edit further. I'm pretty pleased with it (for now 😄).