Add briefs for the library core structures.

LUFA/Drivers/USB/Class/Host/StillImage.h

@@ -31,6 +31,8 @@
 /** \file
  *  \brief Host mode driver for the library USB Still Image Class driver.
  *
+ *  Host mode driver for the library USB Still Image Class driver.
+ *
  *  \note This file should not be included directly. It is automatically included as needed by the class driver
  *        dispatch header located in LUFA/Drivers/USB/Class/StillImage.h.
  */
@@ -71,6 +73,12 @@
 			#define SI_ERROR_LOGICAL_CMD_FAILED              0x80
 
 		/* Type Defines: */
+			/** \brief Still Image Class Host Mode Configuration and State Structure.
+			 *
+			 *  Class state structure. An instance of this structure should be made within the user application,
+			 *  and passed to each of the Still Image class driver functions as the SIInterfaceInfo parameter. This
+			 *  stores each Still Image interface's configuration and state information.
+			 */
 			typedef struct
 			{
 				const struct