doc: Update netbsd/README regarding curses support #1178

Job	Run time
build-dragonflybsd-latest-gcc	2m 50s
build-macos-latest-clang	43s
build-netbsd-latest-gcc	2m 57s
build-freebsd-latest-clang	2m 32s
build-openbsd-latest-clang	3m 48s
build-solaris-latest-gcc	3m 43s
build-ubuntu-latest-clang-analyzer	1m 20s
build-ubuntu-latest-clang-sanitizer	1m 7s
build-ubuntu-latest-full-featured-clang	1m 3s
build-ubuntu-latest-full-featured-gcc	53s
build-ubuntu-latest-gcc-static	1m 11s
build-ubuntu-latest-minimal-clang	1m 1s
build-ubuntu-latest-minimal-gcc	43s
build-ubuntu-latest-pcp	24s
lint-pcp-config	9s
lint-whitespace	2s
	24m 26s

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