Update C++ documentation to state that C++17 is required #1059

Job	Run time
cpp-lib-build (macos-12, clang, ON)	4m 21s
cpp-lib-build (macos-12, clang, OFF)	3m 40s
build (macos-12, tool)	2m 14s
cpp-lib-build (macos-12, gcc, ON)	3m 32s
build (macos-12, cpp)	16m 18s
cpp-lib-build (macos-12, gcc, OFF)	3m 56s
build (macos-12, csharp)	6m 30s
cpp-lib-build (ubuntu-20.04, clang, ON)	3m 17s
build (macos-12, dart)	6m 54s
cpp-lib-build (ubuntu-20.04, clang, OFF)	3m 33s
build (macos-12, go)	4m 45s
cpp-lib-build (ubuntu-20.04, gcc, ON)	4m 29s
build (macos-12, java)	2m 2s
cpp-lib-build (ubuntu-20.04, gcc, OFF)	5m 10s
build (macos-12, javascript)	2m 0s
cpp-lib-build (windows-2022, clang, ON)	4m 25s
build (macos-12, typescript)	22m 42s
cpp-lib-build (windows-2022, clang, OFF)	5m 40s
build (macos-12, php)	2m 9s
cpp-lib-build (windows-2022, cl)	4m 40s
build (macos-12, python3)	1m 50s
build (ubuntu-20.04, tool)	1m 9s
build (ubuntu-20.04, cpp)	17m 28s
build (ubuntu-20.04, csharp)	5m 12s
build (ubuntu-20.04, dart)	3m 44s
build (ubuntu-20.04, go)	2m 33s
build (ubuntu-20.04, java)	1m 15s
build (ubuntu-20.04, javascript)	1m 37s
build (ubuntu-20.04, typescript)	10m 2s
build (ubuntu-20.04, php)	1m 24s
build (ubuntu-20.04, python3)	1m 12s
build (windows-2022, tool)	1m 33s
build (windows-2022, cpp)	21m 24s
build (windows-2022, csharp)	7m 30s
build (windows-2022, dart)	4m 31s
build (windows-2022, go)	5m 51s
build (windows-2022, java)	1m 55s
build (windows-2022, javascript)	2m 21s
build (windows-2022, typescript)	20m 17s
build (windows-2022, php)	1m 59s
build (windows-2022, python3)	1m 48s
	3h 48m 52s

Provide feedback