Maybe you can make a topic explaining how different aspects of a Discourse search work. For example:
Search short explanation
Advanced Search
This feature is hiding near the search bar. It’s commonly known as options and once you press it, the Advanced Search section opens. There, you will find many filters that will help you track the topic you are looking for easier and quicker.
Ever wanted to filter one specific topic but you didn’t know how exactly to do it? As you might have already guessed it, there is a way to do that. Once you have entered a topic, press the search icon 
and tick the small box that appears under the search bar → 
Once you have done that, search for keywords and discourse will automatically track them down for you.
Credits to @Thomas_G for this whole section