Revise description of named arrays in create-cli.rakudoc (#4719)

It's not true that other subs can't use named arrays: they just work a little different than in sub MAIN

Author: arkiuat

doc/Language/create-cli.rakudoc

@@ -294,9 +294,9 @@ Usage:
 
 =head2 Named arrays
 
-The MAIN subroutine can also use a kind of named parameter not available
-to ordinary subs: the named array.  This enables, for instance, providing
-two different short arrays as arguments on a command line.
+The MAIN subroutine can also use a different kind of named parameter: the named array.
+This enables, for instance, providing two different short arrays as arguments on a
+command line.
 
 Declare a named-array parameter with C<:@> in sub MAIN's signature: