Adds definition for osname refs #2800

doc/Type/VM.pod6

@@ -7,7 +7,8 @@
     class VM does Systemic { }
 
 Built-in class for providing information about the virtual machine in which
-Perl 6 is running. Usually accessed through the L<$*VM|/language/variables#index-entry-%24*VM> dynamic variable.
+Perl 6 is running. Usually accessed through the
+L<$*VM|/language/variables#index-entry-%24*VM> dynamic variable.
 
 =head1 Methods
 
@@ -33,6 +34,11 @@ Instance method returning the name of the VM object.
 
 =head2 method osname
 
+Defined as:
+
+    multi method osname(VM:U:)
+    multi method osname(VM:D:)
+
 Instance / Class method returning the name of the Operating System, as known
 by the configuration of the VM object / currently running virtual machine.