Add RFC for CTAD in blocked_nd_range #3521

Job	Run time
copyright_check	4s
codespell	55s
examples_clang-format	8s
examples_ubuntu-latest_g++_cxx14_relwithdebinfo_preview=OFF	3m 45s
ubuntu-latest_g++_cxx14_relwithdebinfo_preview=OFF	19m 34s
examples_ubuntu-20.04_g++_cxx17_release_preview=ON	3m 59s
ubuntu-20.04_g++_cxx17_release_preview=ON	17m 23s
examples_ubuntu-20.04_g++-10_cxx20_debug_preview=ON	4m 42s
ubuntu-20.04_g++-10_cxx20_debug_preview=ON	14m 6s
ubuntu-22.04_g++-11_cxx20_release_preview=ON-DBUILD_SHARED_LIBS=OFF	17m 4s
examples_macos-15_clang++_cxx14_relwithdebinfo_preview=ON	2m 41s
macos-14_clang++_cxx14_relwithdebinfo_preview=ON	12m 31s
macos-13_clang++_cxx20_release_preview=ON-DBUILD_SHARED_LIBS=OFF	18m 6s
python_module_test_ubuntu_latest	35s
examples_windows_cl2019_cxx14_relwithdebinfo_preview=ON	5m 59s
windows_cl2019_cxx14_relwithdebinfo_preview=ON	14m 0s
examples_windows_cl2022_cxx17_relwithdebinfo_preview=OFF	5m 47s
windows_cl2019_cxx20_release_preview=ON-DBUILD_SHARED_LIBS=OFF	20m 53s
windows_cl2022_cxx17_relwithdebinfo_preview=OFF	14m 49s
documentation	52s
pages	0s
	2h 57m 53s

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