Fix EVALFILE signature / hint there's encoding stuff involved

Author: zoffixznet

doc/Type/Cool.pod6

@@ -1338,10 +1338,10 @@ EVAL "use v5.20; say 'Hello from perl5!'", :lang<Perl5>;
 
 Defined as:
 
-    sub EVALFILE(Cool $filename, :$lang = { ... })
+    sub EVALFILE($filename where Blob|Cool, :$lang = 'perl6')
 
 Slurps the specified file and evaluates it. Behaves the same way as C<EVAL>
-with regard to both scoping and the C<$lang> parameter. Evaluates to the value
+with regard to L<Blob> decoding, scoping, and the C<$lang> parameter. Evaluates to the value
 produced by the final statement in the file.
 
 =for code