quote: fix broken sq_quote_buf() related comment

Since 77d604c (Enhanced sq_quote(), 10 Oct 2005), the
comment at the beginning of quote.c is broken.
Let's fix it.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

quote.c

@@ -7,6 +7,7 @@ int quote_path_fully = 1;
 /* Help to copy the thing properly quoted for the shell safety.
  * any single quote is replaced with '\'', any exclamation point
  * is replaced with '\!', and the whole thing is enclosed in a
+ * single quote pair.
  *
  * E.g.
  *  original     sq_quote     result