gitweb: Update config file example for snapshot feature in gitweb/INSTALL

Commit a3c8ab30a54c30a6a434760bedf04548425416ef by Matt McCutchen
  "gitweb: snapshot cleanups & support for offering multiple formats"
introduced new format of $feature{'snapshot'}{'default'} value. Update
"Config file example" in gitweb/INSTALL accordingly.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

gitweb/INSTALL

diff --git a/gitweb/INSTALL b/gitweb/INSTALL
index 6328e26..9cd5b0a 100644
--- a/gitweb/INSTALL
+++ b/gitweb/INSTALL
@@ -116,7 +116,7 @@
 	$feature{'pickaxe'}{'default'} = [1];
 	$feature{'pickaxe'}{'override'} = 1;
 
-	$feature{'snapshot'}{'default'} = ['x-gzip', 'gz', 'gzip'];
+	$feature{'snapshot'}{'default'} = ['zip', 'tgz'];
 	$feature{'snapshot'}{'override'} = 1;