check-ignore: correct documentation about output

By default git check-ignore shows only the filenames that will be
ignored, not the pattern that causes their exclusion. Instead of moving
the partial exclude pattern precendence information to the -v option
where it belongs, link to gitignore(5) which describes this more
thoroughly.

Signed-off-by: Dennis Kaarsemaker <dennis@kaarsemaker.net>
Signed-off-by: Jeff King <peff@peff.net>

Documentation/git-check-ignore.txt

@@ -16,10 +16,9 @@ DESCRIPTION
 -----------
 
 For each pathname given via the command-line or from a file via
-`--stdin`, show the pattern from .gitignore (or other input files to
-the exclude mechanism) that decides if the pathname is excluded or
-included.  Later patterns within a file take precedence over earlier
-ones.
+`--stdin`, check whether the file is excluded by .gitignore (or other
+input files to the exclude mechanism) and output the path if it is
+excluded.
 
 By default, tracked files are not shown at all since they are not
 subject to exclude rules; but see `--no-index'.
@@ -32,7 +31,8 @@ OPTIONS
 
 -v, --verbose::
 	Also output details about the matching pattern (if any)
-	for each given pathname.
+	for each given pathname. For precedence rules within and
+	between exclude sources, see linkgit:gitignore[5].
 
 --stdin::
 	Read pathnames from the standard input, one per line,