Putting "duckduckgo bang" into DDG itself produces results that are ... not helpful. At any rate, nothing on the first page looks like it has any chance of answering the question.
But "!g duckduckgo bang" gives me https://duckduckgo.com/bang as the first hit (this is a high-level description of the bang feature), followed by https://duckduckgo.com/bang_lite.html (which has the actual complete list right there), followed by someone's list of the 25 allegedly-most-useful DDG bangs. Most of the rest of the first-page hits are also informative -- they're things like Reddit and HN discussions of the bang features.
I think this is actually the clearest case I've seen since switching to DDG where Google had demonstrably more useful results. Which is kinda ironic.