cfg80211: Improve connection quality maintenance docs in nl80211.h

In nl80211.h, be a little more elaborate in the docs for the definitions
NL80211_ATTR_CQM_RSSI_THOLD and NL80211_ATTR_CQM_RSSI_HYST.
Reported-by: Luis R. Rodriguez <mcgrof@gmail.com>
Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/nl80211.h

@@ -1600,8 +1600,12 @@ enum nl80211_ps_state {
 /**
  * enum nl80211_attr_cqm - connection quality monitor attributes
  * @__NL80211_ATTR_CQM_INVALID: invalid
- * @NL80211_ATTR_CQM_RSSI_THOLD: RSSI threshold in dBm (zero to disable)
- * @NL80211_ATTR_CQM_RSSI_HYST: RSSI hysteresis in dBm
+ * @NL80211_ATTR_CQM_RSSI_THOLD: RSSI threshold in dBm. This value specifies
+ *	the threshold for the RSSI level at which an event will be sent. Zero
+ *	to disable.
+ * @NL80211_ATTR_CQM_RSSI_HYST: RSSI hysteresis in dBm. This value specifies
+ *	the minimum amount the RSSI level must change after an event before a
+ *	new event may be issued (to reduce effects of RSSI oscillation).
  * @NL80211_ATTR_CQM_RSSI_THRESHOLD_EVENT: RSSI threshold event
  * @__NL80211_ATTR_CQM_AFTER_LAST: internal
  * @NL80211_ATTR_CQM_MAX: highest key attribute