Documentation review with Simon, minor changes

src/include/lwip/api.h

@@ -275,6 +275,7 @@ err_t   netconn_bind(struct netconn *conn, const ip_addr_t *addr, u16_t port);
 err_t   netconn_connect(struct netconn *conn, const ip_addr_t *addr, u16_t port);
 err_t   netconn_disconnect (struct netconn *conn);
 err_t   netconn_listen_with_backlog(struct netconn *conn, u8_t backlog);
+/** @ingroup netconn_tcp */
 #define netconn_listen(conn) netconn_listen_with_backlog(conn, TCP_DEFAULT_LISTEN_BACKLOG)
 err_t   netconn_accept(struct netconn *conn, struct netconn **new_conn);
 err_t   netconn_recv(struct netconn *conn, struct netbuf **new_buf);

src/include/lwip/pbuf.h

@@ -114,8 +114,7 @@ typedef enum {
 /** indicates this pbuf includes a TCP FIN flag */
 #define PBUF_FLAG_TCP_FIN   0x20U
 
-/** Main payload buffer struct
- */
+/** Main packet buffer struct */
 struct pbuf {
   /** next pbuf in singly linked pbuf chain */
   struct pbuf *next;

src/include/lwip/sys.h

@@ -39,14 +39,17 @@
  * @ingroup infrastructure
  * @verbinclude "sys_arch.txt"
  *
- * @defgroup sys_sem Semaphores
+ * @defgroup sys_os OS abstraction layer
  * @ingroup sys_layer
  *
+ * @defgroup sys_sem Semaphores
+ * @ingroup sys_os
+ *
  * @defgroup sys_mutex Mutexes
- * @ingroup sys_layer
+ * @ingroup sys_os
  *
  * @defgroup sys_mbox Mailboxes
- * @ingroup sys_layer
+ * @ingroup sys_os
  *
  * @defgroup sys_time Time
  * @ingroup sys_layer
@@ -55,7 +58,7 @@
  * @ingroup sys_layer
  *
  * @defgroup sys_thread Threads
- * @ingroup sys_layer
+ * @ingroup sys_os
  */
 
 #ifndef LWIP_HDR_SYS_H
@@ -359,7 +362,6 @@ void sys_init(void);
 
 #ifndef sys_jiffies
 /**
- * @ingroup sys_time
  * Ticks/jiffies since power up.
  */
 u32_t sys_jiffies(void);