avoid pluralizing with 's

(also remove 'ss)

Author: coke

doc/Type/Str.pod6

@@ -730,7 +730,7 @@ returns C<Any>.
     my $match = $some-string.subst-mutate(/foo/, "string");
     say $some-string;  #-> Some string
     say $match;        #-> ｢foo｣
-    $some-string.subst-mutate(/<[oe]>/, '', :g); # remove all o'ss and e's, notice the :g named argument from .subst
+    $some-string.subst-mutate(/<[oe]>/, '', :g); # remove every o and e, notice the :g named argument from .subst
 
 =head2 routine substr