Fix Proc::Async.new

- There's no :$path, *@Args candidate
- There's no `:r` argument
- Include the positional multi
- Include :enc and :translate-nl args

Author: zoffixznet

doc/Type/Proc/Async.pod6

@@ -49,15 +49,21 @@ An example that opens an external program for writing:
 
 =head2 method new
 
-    method new(:$path, *@args, :$w, :$r --> Proc::Async:D)
+    multi method new(*@ ($path, *@args), :$w, :$enc, :$translate-nl --> Proc::Async:D)
+    multi method new(   :$path, :@args,  :$w, :$enc, :$translate-nl --> Proc::Async:D)
 
 Creates a new C<Proc::Async> object with external program name or path C<$path>
 and the command line arguments C<@args>.
 
 If C<:w> is passed to C<new>, then a pipe to the external program's standard
 input stream (stdin) is opened, to which you can write with C<write> and
 C<say>.
-If C<:r> is present then you can tap the processes stdout and stderr.
+
+The C<:enc> specifies L<the encoding|/type/IO::Handle#method_encoding> for streams
+(can still be overriden in individual methods) and defaults to C<utf8>.
+
+If C<:translate-nl> is set to C<True> (default value), OS-specific newline
+terminators (e.g. C<\r\n> on Windows) will be automatically translated to C<\n>.
 
 =head2 method stdout