Doc: tweak +pemap offset description #167

Job	Run time
changa_netlrts-linux-x86_64	6m 11s
buildold_netlrts-linux-x86_64	18m 38s
cuda_netlrts-linux-x86_64_buildonly	10m 50s
charm4py_netlrts-linux-x86_64_tcp	6m 7s
doc	44s
multicore-darwin-x86_64_projections	1s
mpi-linux-x86_64	53m 33s
mpi-linux-x86_64_syncft	13m 16s
namd_netlrts-linux-x86_64	11m 53s
netlrts-darwin-x86_64	1s
netlrts-linux-i386	17m 51s
netlrts-linux-x86_64	16m 24s
netlrts-linux-x86_64_smp	25m 13s
netlrts-linux-x86_64_syncft	10m 54s
shellcheck	6s
spack_ubuntu-latest	39m 31s
spack_macos-12	1s
ucx-linux-x86_64_openpmix	17m 0s
verbs-linux-x86_64_smp	16m 22s
netlrts-win-x86_64_mingw64	17m 40s
	4h 42m 16s

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