Update README.md

Author: MikeDvorskiy

rfcs/proposed/zip_view/README.md

@@ -16,7 +16,7 @@ with the same API and functionality as `std::ranges::zip_view`.
 - compilable with C++20 version (minimum)
 - API-compliant with `std::ranges::zip_view`
 - random accessible view; the "underlying" views also should be random accessible
-- in case of a device usage: a device copyable view itself and the "underlying" views also should be device copyable
+- in case of a device usage: a device copyable view if the all "underlying" views are device copyable views
 
 `oneapi::dpl::ranges::zip_view::iterator` should be:
 - value-swappable (https://en.cppreference.com/w/cpp/named_req/ValueSwappable)