Documentation/CodingStyle: flesh out if-else examples

There is a missing case for "Chapter 3: Placing Braces and Spaces".  We
often know we should not use braces where a single statement.  The first
case is:

	if (condition)
		action();

Another case is:

	if (condition)
		do_this();
	else
		do_that();

However, I can not find a description of the second case.

Signed-off-by: Harry Wei <harryxiyou@gmail.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>