CodingStyle: add networking specific block comment style

The block comment style in net/ and drivers/net is non-standard.
Document it.
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: "Allan, Bruce W" <bruce.w.allan@intel.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/CodingStyle

@@ -454,6 +454,16 @@ The preferred style for long (multi-line) comments is:
 	 * with beginning and ending almost-blank lines.
 	 */
 
+For files in net/ and drivers/net/ the preferred style for long (multi-line)
+comments is a little different.
+
+	/* The preferred comment style for files in net/ and drivers/net
+	 * looks like this.
+	 *
+	 * It is nearly the same as the generally preferred comment style,
+	 * but there is no initial almost-blank line.
+	 */
+
 It's also important to comment data, whether they are basic types or derived
 types.  To this end, use just one data declaration per line (no commas for
 multiple data declarations).  This leaves you room for a small comment on each