I totally agree with the sentiment represented here but thinking linking someone to this is a bad way to handle the situation with others. I think it’s best handled by asking them after they make one of these requests and they get their answer. Linking to external sites feels passive aggressive to most people who are just trying to be nice.
But it's the kind of thing you can put in your Slack status so that the moment someone opens up a DM with you, they might see it, read it, and then know, all before they've typed out their first message.
Yes, usually in real life unless it's a close friend I just don't respond to "Hello" until I get something more. It's not aggressive, it's just me waiting until I have a question.
Close friends get a pass because their "hello" might just in some cases mean "hey I'm lonely and want someone to talk to".