Add newline to arc_tool doc output, a=chris

diff --git a/bin/arc_tool.php b/bin/arc_tool.php
index 6925f8c51..7a3e2b05e 100755
--- a/bin/arc_tool.php
+++ b/bin/arc_tool.php
@@ -436,7 +436,7 @@ class ArcTool implements CrawlConstants
         echo "php arc_tool.php info bundle_name //return info about\n".
             "//documents stored in archive.\n\n";
         echo "php arc_tool.php show bundle_name start num //outputs\n".
-            "//items start through num from bundle_name\n";
+            "//items start through num from bundle_name\n\n";
         echo "php arc_tool.php reindex bundle_name \n".
             "//reindex the word dictionary in bundle_name\n";
         exit();