cpu_features: Update hints in README #297

Job	Run time
build-macos (macos-latest)	58s
Build on ubuntu-20.04 g++-7	47s
build-macos (flyci-macos-large-latest-m2)	19s
Build on ubuntu-20.04 g++-8	51s
Build on ubuntu-latest g++-9	1m 16s
Build static on ubuntu-latest	1m 19s
Build on ubuntu-latest g++-10	58s
Build on ubuntu20.04 aarch64 g++-8	7m 24s
Build on ubuntu-20.04 clang-7	52s
Build on ubuntu20.04 aarch64 g++-9	7m 23s
Build on ubuntu-20.04 clang-8	54s
build-windows	1m 35s
Build on ubuntu20.04 aarch64 g++-10	6m 42s
Build on ubuntu-20.04 clang-9	59s
Build on ubuntu-20.04 clang-10	55s
Build on ubuntu22.04 aarch64 g++-12	7m 27s
Build on ubuntu-20.04 clang-11	53s
Build on ubuntu20.04 aarch64 clang-9	10m 45s
Build on ubuntu-latest clang-12	56s
Build on ubuntu20.04 aarch64 clang-10	12m 5s
Build on ubuntu-latest clang-13	59s
Build on ubuntu22.04 aarch64 clang-14	10m 53s
Build on ubuntu-latest clang-14	54s
Build on ubuntu22.04 armv7 g++	7m 26s
Build on ubuntu22.04 ppc64le g++-12	8m 10s
Build on ubuntu22.04 s390x g++-12	6m 12s
Build on ubuntu22.04 riscv64 g++-12	6m 54s
	1h 46m 46s

Provide feedback