changed the documentation of `FamilyPcgs` #4459

Job	Run time
testinstall - - ubuntu-latest	4m 57s
teststandard - - ubuntu-latest	41m 48s
testmanuals - - ubuntu-latest	9m 56s
testexpect testmockpkg testspecial test-compile testlibgap testkernel - - ubuntu-latest	4m 24s
testpackages testinstall-loadall - - ubuntu-latest	13m 55s
makemanuals testmakeinstall - GAPPREFIX=/tmp/gapprefix CONFIGFLAGS="--prefix=/tmp/gapprefix" NO_COVERAGE=1 - ubuntu-latest	8m 2s
teststandard - ABI=32 CONFIGFLAGS="" - ubuntu-20.04	52m 17s
testinstall - HPCGAP=yes ABI=64 - ubuntu-latest	35m 42s
testmockpkg testinstall - BOOTSTRAP_MINIMAL=yes - macos-latest	8m 12s
testbugfix - CONFIGFLAGS="--enable-memory-checking" - ubuntu-latest	35m 44s
testbuildsys testmockpkg testinstall - NO_COVERAGE=1 ABI=64 BUILDDIR=out-of-tree CONFIGFLAGS="--enable-valgrind" - ubuntu-latest	6m 3s
testbuildsys testmockpkg testinstall - NO_COVERAGE=1 ABI=32 BUILDDIR=out-of-tree CONFIGFLAGS="" - ubuntu-20.04	4m 12s
testinstall - JULIA=yes CONFIGFLAGS="--enable-debug --disable-Werror" - ubuntu-20.04	15m 18s
testmockpkg testinstall - - windows-2019	14m 36s
Send Slack notification on status change	6s
	4h 15m 12s

Provide feedback