fix example

Author: gfldex

doc/Language/typesystem.pod6

@@ -218,7 +218,7 @@ Both take a string as argument, for C<:ver> the string is converted to a
 L<Version|/type/Version> object. To query a roles version and auther use
 C<.^ver> and C<^.auth>.
 
-    class R:ver<4.2.3>:auth<me@here.local> {}
+    role R:ver<4.2.3>:auth<me@here.local> {}
     say [R.^ver, R.^auth];
     # OUTPUT«[v4.2.3 me@here.local]␤»