Merge branch 'doc-mptcp-new-general-doc-and-fixes'

Matthieu Baerts says:

====================
doc: mptcp: new general doc and fixes

A general documentation about MPTCP was missing since its introduction
in v5.6. The last patch adds a new 'mptcp' page in the 'networking'
documentation.

The first patch is a fix for a missing sysctl entry introduced in v6.10
rc0, and the second one reorder the sysctl entries.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
====================

v2: https://lore.kernel.org/r/20240528-upstream-net-20240520-mptcp-doc-v2-0-47f2d5bc2ef3@kernel.org
v1: https://lore.kernel.org/r/20240520-upstream-net-20240520-mptcp-doc-v1-0-e3ad294382cb@kernel.org

Link: https://lore.kernel.org/r/20240530-upstream-net-20240520-mptcp-doc-v3-0-e94cdd9f2673@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>