docs: add changelog entry for niche-optimization #2

Job	Run time
Check Credentials for jobs that need JSON credentials	3s
bench-binsize	-1s
Build FFI binaries	-1s
WASM Demo	-1s
bench-perf	-1s
bench-memory	-1s
release-ffi-libs	0s
Rust docs	0s
Kotlin docs	0s
C++ docs	-1s
Dart docs	-1s
TypeScript docs	-1s
Deploy to GitHub Pages	-1s
	-6s

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