cpu_features: Update hints in README #298

Job	Run time
build-macos (macos-latest)	59s
build-macos (flyci-macos-large-latest-m2)	27s
Build on ubuntu-20.04 g++-7	46s
build-windows	1m 53s
Build on ubuntu20.04 aarch64 g++-8	7m 4s
Build on ubuntu-20.04 g++-8	55s
Build on ubuntu20.04 aarch64 g++-9	7m 8s
Build on ubuntu-latest g++-9	56s
Build on ubuntu-latest g++-10	59s
Build on ubuntu20.04 aarch64 g++-10	7m 2s
Build on ubuntu-20.04 clang-7	1m 0s
Build on ubuntu22.04 aarch64 g++-12	6m 59s
Build on ubuntu-20.04 clang-8	1m 19s
Build on ubuntu20.04 aarch64 clang-9	10m 51s
Build on ubuntu-20.04 clang-9	1m 27s
Build on ubuntu20.04 aarch64 clang-10	11m 7s
Build on ubuntu-20.04 clang-10	58s
Build on ubuntu22.04 aarch64 clang-14	11m 11s
Build on ubuntu-20.04 clang-11	1m 19s
Build on ubuntu22.04 armv7 g++	6m 49s
Build on ubuntu-latest clang-12	1m 0s
Build on ubuntu-latest clang-13	1m 1s
Build on ubuntu22.04 ppc64le g++-12	6m 41s
Build on ubuntu-latest clang-14	1m 34s
Build on ubuntu22.04 s390x g++-12	6m 4s
Build on ubuntu22.04 riscv64 g++-12	6m 37s
Build static on ubuntu-latest	1m 10s
	1h 45m 16s

Provide feedback