include/zephyr/net: Add 'brief' to group description

[jukkar]

So it doesn't extend previous directive.

This is cherry-picked from #61994 as that PR might take some time to get merged and the change makes sense.
FYI @edersondisouza

[kartben]

@jukkar
Obviously not opposed to the change as it's sometimes nice to be explicit, but where is the problem showing? @brief is implicit in this instance, and AFAICT it's looking OK everywhere I looked, i.e. https://docs.zephyrproject.org/latest/connectivity/networking/api/wifi.html#api-reference and https://docs.zephyrproject.org/latest/doxygen/html/group__wifi__mgmt.html#details

Just pointing it out to make sure that this is not instead the symptom of an issue in #61994.

[jukkar]

Just pointing it out to make sure that this is not instead the symptom of an issue in #61994.

Ok, could be a side effect of something else but anyway we have the @brief strings in other headers so it should make no harm to have it here too.