clarify that the condition list is an "all" list.

Author: Lokathor

text/0000-result_ffi_guarantees.md

@@ -28,7 +28,7 @@ I'm not sure how to write a "guide" portion of this that's any simpler than the
 When either of these two `core` types:
 
 * `Option<T>`
-* `Result<T, E>` where either `T` or `E`:
+* `Result<T, E>` where either `T` or `E` meet all of the following conditions:
   * Are a zero-sized type with alignment 1 (a "1-ZST").
   * Either have no fields (eg: `()` or `struct Foo;`) or have `repr(transparent)` if there are fields.
   * Do not have the `#[non_exhaustive]` attribute.