Add missing doxygen style comments to XXH3 family #672

Job	Run time
Linux x64 check results consistency	25s
macos-11	44s
macos-12	52s
Linux x64 cmake unofficial build test	11s
QEMU ARM	1m 47s
QEMU AARCH64	6m 23s
QEMU PPC64LE	2m 8s
QEMU PPC64	2m 3s
QEMU S390X	1m 59s
QEMU MIPS	1m 18s
QEMU M68K	1m 33s
QEMU RISC-V	1m 16s
QEMU ARM, gcc-10	1m 57s
QEMU AARCH64, gcc-10	4m 26s
QEMU PPC64LE, gcc-10	1m 24s
QEMU PPC64, gcc-10	1m 35s
QEMU S390X, gcc-10	2m 50s
QEMU MIPS, gcc-10	1m 23s
QEMU ARM, gcc-9	1m 52s
QEMU PPC64LE, gcc-9	1m 41s
QEMU PPC64, gcc-9	1m 30s
QEMU S390X, gcc-9	2m 42s
QEMU MIPS, gcc-9	1m 17s
QEMU ARM, gcc-8	1m 40s
QEMU PPC64LE, gcc-8	1m 41s
QEMU PPC64, gcc-8	1m 42s
QEMU S390X, gcc-8	2m 16s
Linux x64 misc tests	1m 45s
Ubuntu Node 16.x WebAssembly/asm.js tests	1m 11s
Ubuntu Node 17.x WebAssembly/asm.js tests	1m 7s
Ubuntu Node 18.x WebAssembly/asm.js tests	1m 0s
Windows mingw64	2m 49s
Windows mingw32	3m 37s
VC++ 2022, x64	1m 28s
VC++ 2022, Win32	56s
VC++ 2022, ARM	36s
VC++ 2022, ARM64	1m 17s
VC++ 2019, x64	1m 5s
VC++ 2019, Win32	1m 46s
VC++ 2019, ARM	49s
VC++ 2019, ARM64	2m 30s
CC=cc, ubuntu-latest	1m 32s
CC=gcc, ubuntu-latest	1m 15s
CC=gcc-12, ubuntu-22.04	1m 53s
CC=gcc-11, ubuntu-22.04	1m 27s
CC=gcc-10, ubuntu-22.04	1m 21s
CC=gcc-9, ubuntu-22.04	1m 25s
CC=gcc-8, ubuntu-20.04	1m 17s
CC=gcc-7, ubuntu-20.04	1m 45s
CC=clang, ubuntu-latest	1m 9s
CC=clang-12, ubuntu-22.04	1m 14s
CC=clang-11, ubuntu-22.04	1m 13s
CC=clang-10, ubuntu-20.04	1m 10s
CC=clang-9, ubuntu-20.04	1m 18s
CC=clang-8, ubuntu-20.04	1m 30s
CC=clang-7, ubuntu-20.04	1m 29s
CC=clang-6.0, ubuntu-20.04	1m 22s
	1h 34m 51s

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