Reword desc of IO::Path.child

6.e is too much future-telling and we might not do the originally-planned
".child-secure" stuff anyway since it's not bulletproof and still has a race
and we'll probably implement this feature through .open instead.

Author: zoffixznet

doc/Type/IO/Path.pod6

@@ -151,11 +151,9 @@ Defined as:
 
     method child(IO::Path:D: Str() $childname --> IO::Path:D)
 
-Alias for L«C<.add>|/routine/add». B<NOTE:> C<.child> will be switched to
-secure version around 6.e release time, which will C<fail()> with non-child
-paths and is also slower, since it has to do more work. Use
-L«C<.add>|/routine/add» if your code does not need to guarantee the added
-path is in fact a child path.
+Alias for L«C<.add>|/routine/add». B<NOTE:> C<.child> exists largely for
+backwards-compatibility reasons and may become deprecated in future language
+versions. For any new code, please use L«C<.add>|/routine/add»
 
 =head2 method cleanup