docs: Update userspace TSO GRE documentation. #6694

Job	Run time
dpdk gcc (ubuntu-24.04)	4s
libreswan (ubuntu-24.04)	5s
linux rpm fedora	4m 32s
linux deb no dpdk	6m 24s
build oss-fuzz fuzzers	2m 53s
osx clang --disable-ssl	1m 31s
clang-analyze-cache	13m 8s
linux gcc --disable-ssl	2m 32s
linux clang --disable-ssl	2m 37s
linux gcc c99	3m 13s
linux clang c99	2m 45s
linux gcc test	8m 30s
linux clang address,undefined test	16m 26s
linux gcc test --enable-shared	11m 41s
linux clang test --enable-shared	12m 57s
linux gcc check check-dpdk dpdk	19m 20s
linux clang check check-dpdk dpdk	19m 47s
linux gcc test -ljemalloc	8m 55s
linux clang test -ljemalloc	8m 46s
linux gcc --enable-afxdp	3m 1s
linux clang --enable-afxdp	2m 46s
linux gcc dpdk --enable-shared	3m 32s
linux clang dpdk --enable-shared	3m 47s
linux gcc dpdk-shared	2m 46s
linux clang dpdk-shared	3m 50s
linux gcc dpdk-shared --enable-shared	5m 10s
linux clang dpdk-shared --enable-shared	3m 53s
linux gcc m32 --disable-ssl	3m 59s
linux gcc check-ovsdb-cluster	6m 53s
linux gcc check-kernel -100	10m 24s
linux gcc check-kernel 100-	17m 12s
linux clang address,undefined check-kernel -100	13m 0s
linux clang address,undefined check-kernel 100-	20m 1s
linux gcc check-offloads -100	9m 29s
linux gcc check-offloads 100-	12m 2s
linux gcc dpdk check-system-userspace	12m 38s
linux clang address,undefined dpdk check-system-userspace	18m 14s
linux gcc dpdk check-system-tso	13m 56s
linux gcc dpdk check-afxdp	12m 3s
clang-analyze	10m 32s
	5h 35m 14s

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