Improve doc of DirectProductFamily

Co-Authored-By: Max Horn <max@quendi.de>

lib/tuples.gd

@@ -198,11 +198,11 @@ DeclareOperation( "DirectProductElementNC",
 ## <Ref Filt="IsDirectProductElement"/> objects
 ## whose <C>i</C>-th component is in <C>ElementsFamily(args[i])</C>.
 ## <P/>
-## Note that a collection in <C>fam</C> must thus not necessarily be a
-## direct product.
+## Note that a collection in <C>fam</C> may not itself be a
+## direct product; it just is a subcollection of a direct product.
 ## Also note that not all direct products in &GAP; are created via these
-## families. For example the elements of a permutation group created via
-## <Ref Func="DirectProduct"/> are not <Ref Filt="IsDirectProductElement"/>
+## families. For example if the arguments to <Ref Func="DirectProduct"/> are permutation groups,
+## then it returns a permutation group as well, whose elements are not <Ref Filt="IsDirectProductElement"/>
 ## objects.
 ## <P/>
 ## <Example><![CDATA[