cmd/link: document that on ELF, GNU build ID is now generated by default

[dmitshur]

A comment on CL 618601 indicated that the change (which fixed #63934 and #68652) should likely be mentioned in Go 1.24 release notes. Filing a release blocking issue to track this.

CC @cherrymui.

[gabyhelp]

Related Code Changes

• cmd/link: on ELF, generate GNU build ID by default
• cmd/go: add support for build IDs with gccgo
• cmd/link: add -buildid flag to write Go build ID to ELF output, same as cmd/compile
• cmd/internal/buildid: skip over GNU build ID from buildid computation
• cmd/link: allow deriving GNU build ID from Go build ID ID

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[gopherbot]

Change https://go.dev/cl/633875 mentions this issue: doc/next: add linker change release notes