add Nl numeric value example

Author: ronaldxs

doc/Language/unicode_texas.pod6

@@ -40,8 +40,8 @@ aren't decimal digit characters, so can't be combined.) For example:
 
 =begin code
 
-  my $var = ⅒ + 2;
-  say $var; # 2.1
+  my $var = ⅒ + 2 + Ⅻ; # here ⅒ is No and Rat and Ⅻ is Nl and Int
+  say $var;              # 14.1
 
 =end code