Add warning about cond

content/en/functions/cond.md

@@ -24,3 +24,9 @@ Example:
 ```
 
 Would emit "goose" if the `$geese` array has exactly 1 item, or "geese" otherwise.
+
+{{% warning %}}
+Whenever you use a `cond` function, *both* variable expressions are *always* evaluated. This means that a usage like `cond false (div 1 0) 27` will throw an error because `div 1 0` will be evaluated *even though the condition is false*.
+
+In other words, the `cond` function does *not* provide [short-circuit evaluation](https://en.wikipedia.org/wiki/Short-circuit_evaluation) and does *not* work like a normal [ternary operator](https://en.wikipedia.org/wiki/%3F:) that will pass over the first expression if the condition returns `false`.
+{{% /warning %}}