Update closures.md to correct a typo

Author: sinansonmez

src/fn/closures.md

@@ -14,7 +14,7 @@ variable names *must* be specified.
 
 Other characteristics of closures include:
 * using `||` instead of `()` around input variables.
-* optional body delimination (`{}`) for a single expression (mandatory otherwise).
+* optional body delimination (`{}`) for a single line expression (mandatory otherwise).
 * the ability to capture the outer environment variables.
 
 ```rust,editable