Clarify LCD_BED_LEVELING requirements

LCD_BED_LEVELING requires PROBE_MANUALLY with auto bed leveling enabled.  See #7396

Marlin/SanityCheck.h

   #if DISABLED(ULTIPANEL)
     #error "LCD_BED_LEVELING requires an LCD controller."
   #elif DISABLED(MESH_BED_LEVELING) && !(HAS_ABL && ENABLED(PROBE_MANUALLY))
-    #error "LCD_BED_LEVELING requires MESH_BED_LEVELING or PROBE_MANUALLY."
+    #error "LCD_BED_LEVELING requires MESH_BED_LEVELING or PROBE_MANUALLY with auto bed leveling enabled."
   #endif
 #endif