net: add documentation to socket.c

Adds missing sphinx documentation to the
socket.c's functions. Also fixes some whitespaces.

I also changed the style of older documentation as an
effort to have an uniform documentation style.
Signed-off-by: Pedro Tammela <pctammela@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/net.h

@@ -83,6 +83,12 @@ enum sock_type {
 
 #endif /* ARCH_HAS_SOCKET_TYPES */
 
+/**
+ * enum sock_shutdown_cmd - Shutdown types
+ * @SHUT_RD: shutdown receptions
+ * @SHUT_WR: shutdown transmissions
+ * @SHUT_RDWR: shutdown receptions/transmissions
+ */
 enum sock_shutdown_cmd {
 	SHUT_RD,
 	SHUT_WR,