fix type typo that broke compilation

Author: coke

doc/Language/system.pod6

@@ -47,7 +47,7 @@ provides a very convenient API for scripts that deal with sets of files.
 Use C<prompt> to have a running program query the user for data:
 
 =begin code
-my Uint $num-iters = prompt "How many iterations to run: ";
+my UInt $num-iters = prompt "How many iterations to run: ";
 =end code
 
 =head1 Running programs synchronously and asynchronously