Added entry on Reduction operators to operators.pod

Author: dha

lib/Language/operators.pod

@@ -1534,6 +1534,29 @@ roles).
 If the C<???> statement is executed, it calls L<&warn>, with the default
 message C<stub code executed>.
 
+=head2 Reduction operators
+
+Any infix operator (except for non-associating operators) can be
+surrounded by square brackets in term position to create a list operator
+that reduces using that operation.
+
+=begin code
+
+    [+] 1, 2, 3;      # 1 + 2 + 3 = 6
+    my @a = (5,6);
+    [*] @a;           # 5 * 6 = 30
+
+=end code
+
+Reduction operators have the same associativity as the operators they are based on.
+
+=begin code
+
+    [-] 4, 3, 2;      # 4-3-2 = (4-3)-2 = -1
+    [**] 4, 3, 2;     # 4**3**2 = 4**(3**2) = 262144
+
+=end code
+
 =head1 Loose AND precedence
 
 =head2 infix C«and»