reset: make the reminder output consistent with "checkout"

git reset without argument displays a summary of the local modification,
like this:

    $ git reset
    Makefile: locally modified

Some people have problems with this; they look like an error message.

This patch makes its output mimic how "git checkout $another_branch"
reports the paths with local modifications.  "git add --refresh --verbose"
is changed in the same way.

It also adds a header to make it clear that the output is informative,
and not an error.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>

builtin-add.c

@@ -106,7 +106,7 @@ static void refresh(int verbose, const char **pathspec)
 		/* nothing */;
 	seen = xcalloc(specs, 1);
 	refresh_index(&the_index, verbose ? REFRESH_IN_PORCELAIN : REFRESH_QUIET,
-		      pathspec, seen);
+		      pathspec, seen, "Unstaged changes after refreshing the index:");
 	for (i = 0; i < specs; i++) {
 		if (!seen[i])
 			die("pathspec '%s' did not match any files", pathspec[i]);