Client: disable mmdb modstore

The service isn't online, and on the long term, mmdb will likekly be
replaced with other services from the modding community.

builtin/mainmenu/tab_mods.lua

@@ -36,7 +36,10 @@ local function get_formspec(tabview, name, tabdata)
 --		"label[0.8,4.2;" .. fgettext("Add mod:") .. "]" ..
 --		TODO Disabled due to upcoming release 0.4.8 and irrlicht messing up localization
 --		"button[0.75,4.85;1.8,0.5;btn_mod_mgr_install_local;".. fgettext("Local install") .. "]" ..
-		"button[0,4.85;5.25,0.5;btn_modstore;".. fgettext("Online mod repository") .. "]"
+
+--		TODO Disabled due to service being offline, and not likely to come online again, in this form
+--		"button[0,4.85;5.25,0.5;btn_modstore;".. fgettext("Online mod repository") .. "]"
+		""
 
 	local selected_mod = nil