Adjust release notes for post-merge feedback

[Mark-Simulacrum]

• Adds musl CVE fix to compiler section
• Removes Cargo section per feedback in the PR (relnotes for 1.95 #155162 (comment))

cc @BoxyUwU (just FYI)

[rustbot]

r? @jieyouxu

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[jieyouxu]

Thanks, r=me unless you want a specific reviewer.