git-difftool(1): fix formatting of --symlink description

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-difftool.txt

@@ -74,8 +74,8 @@ with custom merge tool commands and has the same value as `$MERGED`.
 	'git difftool''s default behavior is create symlinks to the
 	working tree when run in `--dir-diff` mode.
 +
-	Specifying `--no-symlinks` instructs 'git difftool' to create
-	copies instead.  `--no-symlinks` is the default on Windows.
+Specifying `--no-symlinks` instructs 'git difftool' to create copies
+instead.  `--no-symlinks` is the default on Windows.
 
 -x <command>::
 --extcmd=<command>::