Yes, you can do it through the bulk editor in Selling Manager by adding to the item descriptions (this means that rather than be included in the original description section, there will be a separate section underneath that shows the date the info / link was added, with a note saying ''On XX-XX-14 the seller added the following information". You will probably be able to find this on many other seller's listings if you wanted to see what it looks like before doing it - if that's not suitable, AFAIK the only other way is by editing each listing manually).
If you want to add it in that way, select all the listing you want to edit (the bulk editor can do up to 200 listings at a time, but you may find it works better if you do them in smaller batches), then click 'edit selected'. When the editor loads, select all listings again, click the Edit Fields menu, then select Item Description.
Switch the action in the drowpdown menu to 'Edit listings in bulk - add to description'. Then, I'd recommend switching to the HTML editor and inputting the HTML code if you want to format it in any particular way, as the standard editor only gives you text editing choices.
Just as an aside, you have the left navigation menu with direct links to your store categories, plus three direct links to the store home on the listing page - if you wanted the one in the store header, just above the description, to stand out a bit more, you could adjust the dark blue in your store theme (the door is a very similar colour, so it might be overlooked).
