DOC: config: add missing "track-sc0" in action keywords matrix

DOC: config: add missing "track-sc0" in action keywords matrix

In d54e8f8107 ("DOC: config: reorganize actions into their own section"),
"track-sc0" keyword was properly documented but the keyword was not placed
in the action keywords matrix alongside other track-sc* statements. It
was probably overlooked, so let's fix that.

Could be backported up to 2.9 with d54e8f8107.

(cherry picked from commit f94c63021b9d46a5a77540b6b95cf6e60dcbf5e0)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 29b1710c9a86fb41f1c322f68a90d199298696f1)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>