Added docs for Capture.kv

Author: Jan-Olof Hendig

doc/Type/Capture.pod6

@@ -133,6 +133,23 @@ named argument values.
     my $capture = \(2, 3, 5, apples => (red => 2));
     say $capture.values;                              # (2 3 5 red => 2)
 
+=head2 method kv
+
+Defined as:
+
+    multi method kv(Capture:D:) returns Seq:D
+
+Usage:
+
+    $capture.kv
+
+Returns a L<Seq|/type/Seq> of alternating L<keys|#method_keys> and
+L<values|#method_values>. The positional keys and values, if any, comes
+first followed by the named keys and values.
+
+    my $capture = \(2, 3, apples => (red => 2));
+    say $capture.kv;                                  # (0 2 1 3 apples red => 2)
+
 =head2 method Bool
 
 Defined as: