fixup! docs: HashSet and ISet in the changelog and the collection table

The sentence about the null checks of `HashSet` also names the default flat list that is given
as a sequence, and says that `yield!` and `for` of `hashSet { }` do the same.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Author: xperiandri

CHANGELOG.md

@@ -51,7 +51,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `add`, `addRange`, `remove`, `removeRange`, `clear`, `update`, `filter` and `partition` of `HashSet` keep the comparer
   of their input, and the set algebra keeps the comparer of the first hash set; `map`, `choose` and `partitionWith`
   compare with the default comparer of the result type. Every function throws `ArgumentNullException` for a `null` hash
-  set, sequence or array. `unionMany` of an empty sequence returns an empty hash set, as `Set.unionMany` does.
+  set, sequence or array, and for a default flat list that is given as a sequence; `yield!` and `for` of
+  `hashSet { }` do the same. `unionMany` of an empty sequence returns an empty hash set, as `Set.unionMany` does.
   `tryGetValue` returns a `voption`, `choose` takes a function that returns a `voption`, and `partition` and
   `partitionWith` return struct tuples.
 * The set algebra and the relations of `HashSet` take hash sets, as the `Set` functions do. The BCL members that take a