Remove claim that state @A will be supported

perldiag doesn't seem to be the right place to announce future changes to
Perl, especially since this claim was made 9 years ago, in 6dbe945, and
doesn't show any sign of becoming true.

Author: Smylers

pod/perldiag.pod

@@ -2741,11 +2741,10 @@ either consume text or fail.
 
 =item Initialization of state variables in list context currently forbidden
 
-(F) Currently the implementation of "state" only permits the
-initialization of scalar variables in scalar context.  Re-write
-C<state ($a) = 42> as C<state $a = 42> to change from list to scalar
-context.  Constructions such as C<state (@a) = foo()> will be
-supported in a future perl release.
+(F) C<state> only permits initializing a single scalar variable, in scalar
+context. So C<state $a = 42> is allowed, but not C<state ($a) = 42>. To apply
+state semantics to a hash or array, store a hash or array reference in a scalar
+variable.
 
 =item %%s[%s] in scalar context better written as $%s[%s]