docs: Fix route lookup behavior description. #3304

Job	Run time
linux rpm fedora	6m 47s
osx clang --disable-ssl	1m 57s
Prepare container	3m 16s
linux gcc --disable-ssl	2m 46s
linux clang --disable-ssl	2m 40s
linux gcc test -300	9m 17s
linux gcc test 301-600	6m 2s
linux gcc test 601- unstable	6m 21s
linux clang test sanitizers -300	12m 35s
linux clang test sanitizers 301-600	9m 18s
linux clang test sanitizers 601- unstable	10m 35s
linux gcc test -ljemalloc -300	9m 41s
linux gcc test -ljemalloc 301-600	6m 23s
linux gcc test -ljemalloc 601- unstable	6m 26s
linux gcc system-test-dpdk dpdk -100	16m 48s
linux gcc system-test-dpdk dpdk 101- unstable	14m 1s
linux gcc system-test-userspace -100	16m 4s
linux gcc system-test-userspace 101- unstable	12m 49s
linux gcc system-test -100	18m 39s
linux gcc system-test 101- unstable	17m 17s
linux clang system-test sanitizers -100	19m 59s
linux clang system-test sanitizers 101- unstable	19m 17s
linux x86 gcc --disable-ssl	2m 30s
	3h 51m 28s

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