Document Pair.new

Addresses user's confusion about possible accepted args in:
RT#131339: https://rt.perl.org/Ticket/Display.html?id=131339

Author: zoffixznet

doc/Type/Pair.pod6

@@ -50,6 +50,15 @@ Any variable can be turned into a C<Pair> of its name and its value.
 
 =head1 Methods
 
+=head2 method new
+
+Defined as:
+
+    multi method new(Pair: Mu  $key, Mu  $value)
+    multi method new(Pair: Mu :$key, Mu :$value)
+
+Constructs a new L<Pair> object.
+
 =head2 method ACCEPTS
 
 Defined as: