[S05] Remove redundant word

Author: ShimmerFairy

S05-regex.pod

@@ -708,7 +708,7 @@ message if that is not the case.
 =item *
 
 The C<:samecase>, C<:samespace> and C<:samemark> modifiers (and their short
-forms) modifiers are only allowed on substitutions (C<s///> and C<s[] = ...>).
+forms) are only allowed on substitutions (C<s///> and C<s[] = ...>).
 
 =item *