You're advertising a Q&A site for ubuntu outside the official ubuntu forums. This is bad for users (especially new ones) as they don't know how to look for help if there are thousands of sites advertised. It's one thing answering a user having a question with this site. It's another thing advertising these sites for general help for users as there's an official forum. You did not advertise this site for anyone having an issue you advertised it as general thing for ubuntu which (if more would make it) would render the ubuntu forums useless. So your advertisement is SPAM, as you advertise some thing you may find usefull in some ways, but most users are confused of having thousands of sites to look after if they have problems.