Add some more info about "is dynamic"

And how it should probably not be used.

Author: lizmat

doc/Type/Variable.pod6

@@ -68,6 +68,22 @@ introspect;         # OUTPUT: «23␤»
 }
 =end code
 
+The C<is dynamic> trait is a rather cumbersome way of creating and accessing
+dynamic variables.  A much easier way is to use the C<* twigil>:
+
+=begin code :allow<B L>
+sub introspect() {
+    say B<$*x>;
+}
+my $*x = 23;
+introspect;         # OUTPUT: «23␤»
+{
+    # not dynamic
+    my $x;
+    introspect()    # dies with an exception of L<type X::Dynamic::NotFound.new|/type/X::Dynamic::NotFound.new>
+}
+=end code
+
 =head2 trait of
 
     multi sub trait_mod:<of>(Mu:U $target, Mu:U $type)