CodingStyle: Document the exception of not splitting user-visible strings, for grepping

Patch reviewers now recommend not splitting long user-visible strings,
such as printk messages, even if they exceed 80 columns.  This avoids
breaking grep.  However, that recommendation did not actually appear
anywhere in Documentation/CodingStyle.

See, for example, the thread at
  http://news.gmane.org/find-root.php?message_id=%3c1312215262.11635.15.camel%40Joe%2dLaptop%3eSigned-off-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/CodingStyle

@@ -80,22 +80,13 @@ available tools.
 The limit on the length of lines is 80 columns and this is a strongly
 preferred limit.
 
-Statements longer than 80 columns will be broken into sensible chunks.
-Descendants are always substantially shorter than the parent and are placed
-substantially to the right. The same applies to function headers with a long
-argument list. Long strings are as well broken into shorter strings. The
-only exception to this is where exceeding 80 columns significantly increases
-readability and does not hide information.
-
-void fun(int a, int b, int c)
-{
-	if (condition)
-		printk(KERN_WARNING "Warning this is a long printk with "
-						"3 parameters a: %u b: %u "
-						"c: %u \n", a, b, c);
-	else
-		next_statement;
-}
+Statements longer than 80 columns will be broken into sensible chunks, unless
+exceeding 80 columns significantly increases readability and does not hide
+information. Descendants are always substantially shorter than the parent and
+are placed substantially to the right. The same applies to function headers
+with a long argument list. However, never break user-visible strings such as
+printk messages, because that breaks the ability to grep for them.
+
 
 		Chapter 3: Placing Braces and Spaces