Document Zen slicing a Seq caches it

Propspec: Raku/roast@7d23fbc
PoV: rakudo/rakudo@b84b090
Closes rakudo/rakudo#2383 R#2383

doc/Language/subscripts.pod6

@@ -320,8 +320,12 @@ object) or an empty list (which returns an empty slice):
     say %bag{*};   # OUTPUT: «(1 3)␤»
     say %bag{()};  # OUTPUT: «()␤»
 
-It is usually used to L<interpolate|/language/quoting#Interpolation:_qq>
-entire arrays / hashes into strings:
+Zen slicing does not
+L<reify|/language/glossary#index-entry-Reify> and for L<List> type merely
+returns the object. It is usually used to
+L<interpolate|/language/quoting#Interpolation:_qq> entire arrays / hashes into strings.
+For L<Seq> type, Zen slice is equivalent to calling a Zen slice on return value
+of L<cache>.
 
     my @words = "cruel", "world";
     say "Hello, @words[]!"  # OUTPUT: «Hello, cruel world!␤»