docs: fix uninitialized pointer bug in opts example code #8

Job	Run time
prepare	2s
Build with Pip (ubuntu-22.04, 3.8, llvm, -march=native)	1m 4s
Build with Pip (ubuntu-22.04, 3.8, llvm, -march=x86-64)	1m 23s
Build with Pip (ubuntu-22.04, 3.8, gcc, -march=native)	53s
Build with Pip (ubuntu-22.04, 3.8, gcc, -march=x86-64)	56s
Build with Pip (ubuntu-22.04, 3.11, llvm, -march=native)	1m 5s
Build with Pip (ubuntu-22.04, 3.11, llvm, -march=x86-64)	1m 23s
Build with Pip (ubuntu-22.04, 3.11, gcc, -march=native)	53s
Build with Pip (ubuntu-22.04, 3.11, gcc, -march=x86-64)	1m 5s
Build with Pip (windows-2022, 3.8, msvc, /arch:AVX2)	12m 7s
Build with Pip (windows-2022, 3.8, msvc, /arch:SSE2)	12m 27s
Build with Pip (windows-2022, 3.8, llvm, /arch:AVX2)	4m 55s
Build with Pip (windows-2022, 3.8, llvm, /arch:SSE2)	4m 22s
Build with Pip (windows-2022, 3.11, msvc, /arch:AVX2)	12m 14s
Build with Pip (windows-2022, 3.11, msvc, /arch:SSE2)	11m 40s
Build with Pip (windows-2022, 3.11, llvm, /arch:AVX2)	4m 30s
Build with Pip (windows-2022, 3.11, llvm, /arch:SSE2)	4m 36s
Build with Pip (macos-13, 3.8, llvm, -march=native)	2m 48s
Build with Pip (macos-13, 3.8, llvm, -march=x86-64)	6m 7s
Build with Pip (macos-13, 3.8, gcc-14, -march=native)	1m 33s
Build with Pip (macos-13, 3.8, gcc-14, -march=x86-64)	1m 48s
Build with Pip (macos-13, 3.11, llvm, -march=native)	3m 43s
Build with Pip (macos-13, 3.11, llvm, -march=x86-64)	3m 12s
Build with Pip (macos-13, 3.11, gcc-14, -march=native)	1m 27s
Build with Pip (macos-13, 3.11, gcc-14, -march=x86-64)	2m 29s
	1h 38m 42s

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