Note IO::Handle.open :r/:mode<ro> are eqv no mode args

Author: zoffixznet

doc/Type/IO/Handle.pod6

@@ -41,7 +41,7 @@ The open mode defaults to non-exclusive, read only (same as specifying
 C<:r>) and can be controlled by a mix of the following arguments:
 
 =begin code :skip-test :allow< B R >
-:r      same as specifying   :mode<ro>
+:r      same as specifying   :mode<ro>  same as specifying nothing
 
 :w      same as specifying   :mode<wo>, :create, :truncate
 :a      same as specifying   :mode<wo>, :create, :append