[docs] remove empty lines (#10999)

src/core/config/parent_search.h

@@ -130,7 +130,6 @@
  * timeout expires.
  *
  * Applicable only if periodic parent search feature is enabled (see `OPENTHREAD_CONFIG_PARENT_SEARCH_ENABLE`).
- *
  */
 #ifndef OPENTHREAD_CONFIG_PARENT_SEARCH_RESELECT_TIMEOUT
 #define OPENTHREAD_CONFIG_PARENT_SEARCH_RESELECT_TIMEOUT (90 * 60)
@@ -141,7 +140,6 @@
  *
  * Specifies the RSS margin over the current parent RSS for allowing selection of a neighboring router as a potential
  * new parent to attach to. Used on FTD child devices.
- *
  */
 #ifndef OPENTHREAD_CONFIG_PARENT_SEARCH_RSS_MARGIN
 #define OPENTHREAD_CONFIG_PARENT_SEARCH_RSS_MARGIN 7

src/core/net/nd6.hpp

@@ -852,7 +852,6 @@ class NeighborSolicitHeader : public Clearable<NeighborSolicitHeader>
 public:
     /**
      * Initializes the Neighbor Solicitation message header.
-     *
      */
     NeighborSolicitHeader(void);
 

src/lib/spinel/spinel.h

@@ -2097,7 +2097,6 @@ enum
     /** Format: `S`
      *
      * The 802.15.4 alternate short address.
-     *
      */
     SPINEL_PROP_MAC_15_4_ALT_SADDR = SPINEL_PROP_MAC__BEGIN + 12,
 

tests/nexus/openthread-core-nexus-config.h

@@ -28,7 +28,6 @@
 
 /**
  * This header file defines the OpenThread core configuration for Nexus simulation
- *
  */
 
 #ifndef OT_CORE_NEXUS_CONFIG_H_