wifi: mac80211: correctly document struct mesh_table

Currently kernel-doc -Wall reports:

net/mac80211/ieee80211_i.h:687: warning: missing initial short description on line:
 * struct mesh_table

So add a short description.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/linux-wireless/a009a21a-56d7-4a1a-aaf9-feefa5acc561@infradead.org/


Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://msgid.link/20240328-mesh_table-kerneldoc-v1-1-174c4df341b1@quicinc.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>