Fix documentation for linkgroups #1359

Job	Run time
macosx (debug, x64)	33s
linux (debug, x64, none, gcc)	15s
macosx (release, x64)	37s
mingw (debug, mingw32)	3m 4s
linux (debug, x64, none, clang)	16s
mingw (debug, mingw64)	3m 52s
linux (debug, x64, contrib, gcc)	31s
windows (debug, Win32, vs2022)	6m 3s
windows (debug, x64, vs2022)	6m 9s
mingw (release, mingw32)	2m 49s
linux (debug, x64, contrib, clang)	34s
windows (release, Win32, vs2022)	6m 10s
mingw (release, mingw64)	3m 55s
windows (release, x64, vs2022)	5m 52s
linux (debug, x64, system, gcc)	29s
linux (debug, x64, system, clang)	37s
linux (release, x64, none, gcc)	15s
freebsd (debug, x64, gcc)	3m 51s
cosmopolitan (debug)	1m 6s
linux (release, x64, none, clang)	14s
freebsd (debug, x64, clang)	3m 40s
linux (release, x64, contrib, gcc)	37s
freebsd (release, x64, gcc)	3m 49s
linux (release, x64, contrib, clang)	40s
freebsd (release, x64, clang)	3m 29s
linux (release, x64, system, gcc)	29s
cosmopolitan (release)	1m 26s
linux (release, x64, system, clang)	34s
ci	1s
	1h 1m 57s

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