Add the following (or something similar) to the part about our sister sites: 


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<h3>We have <a href="http://stackexchange.com/sites/">sister sites</a>:</h3>

- ...
- All these sites are part of the <a href="http://stackexchange.com/sites/">StackExchange network</a>, which covers a broad range of topics. 


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Reason: Thankfully, they are seldom, but I've seen questions here covering topics like games and computer science. Also, I believe most new users don't understand that SF is part of a whole network of sites, and with this line we make the reference explicit, not just an unexplained link in the title of that section.