Doc: tweak +pemap offset description #140

Job	Run time
changa_netlrts-linux-x86_64	6m 9s
cuda_netlrts-linux-x86_64_buildonly	10m 7s
buildold_netlrts-linux-x86_64	18m 53s
charm4py_netlrts-linux-x86_64_tcp	10m 21s
doc	39s
mpi-linux-x86_64_syncft	13m 34s
mpi-linux-x86_64	1h 8m 30s
multicore-darwin-x86_64_projections	19m 9s
namd_netlrts-linux-x86_64	9m 28s
netlrts-darwin-x86_64	25m 45s
netlrts-linux-i386	17m 35s
netlrts-linux-x86_64_smp	25m 32s
netlrts-linux-x86_64_syncft	11m 2s
netlrts-linux-x86_64	15m 57s
netlrts-win-x86_64_mingw64	18m 19s
spack_ubuntu-latest	38m 32s
shellcheck	6s
ucx-linux-x86_64_openpmix	17m 37s
spack_macos-12	39m 2s
verbs-linux-x86_64_smp	16m 16s
	6h 22m 33s

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