Switch out l() syntax to [] in docs (#851)

* Switch out l() syntax to [] in docs

* Using map syntactic sugar as well.

Co-authored-by: gnembon <41132274+gnembon@users.noreply.github.com>

docs/scarpet/language/Operators.md

@@ -253,8 +253,8 @@ flips boolean condition of the expression. Equivalent of `bool(expr)==false`
 !false  => true
 !null  => true
 !5  => false
-!l() => true
-!l(null) => false
+![] => true
+![null] => false
 </pre>
 
 ### `Unpacking Operator ...`