You can get this information from the course logs (Administration->Reports). Select the resource you're interested in, and the Update action, and you should see who updated it, and when.
If you want the name to appear on the resource page itself, you'd have to modify the display() function for each resource type - e.g. for text pages, look in mod/resource/type/text/resource.class.php. Also, the modification date/time is stored in the mdl_resource table, but the user who made the mods is not - you'd have pull the user info. out of the mdl_log table.