First pass at some documentation for combineLatest (#94)

* First pass at some documentation for combineLatest

* Add additional docs for extension methods and AsyncCombineLatest2Sequence structure

Author: phausler

Sources/AsyncAlgorithms/AsyncCombineLatest2Sequence.swift

@@ -9,10 +9,13 @@
 //
 //===----------------------------------------------------------------------===//
 
+/// Creates an asynchronous sequence that combines the latest values from two `AsyncSequence` types
+/// by emitting a tuple of the values.
 public func combineLatest<Base1: AsyncSequence, Base2: AsyncSequence>(_ base1: Base1, _ base2: Base2) -> AsyncCombineLatest2Sequence<Base1, Base2> {
   AsyncCombineLatest2Sequence(base1, base2)
 }
 
+/// An `AsyncSequence` that combines the latest values produced from two asynchronous sequences into an asynchronous sequence of tuples.
 public struct AsyncCombineLatest2Sequence<Base1: AsyncSequence, Base2: AsyncSequence>: Sendable
   where
     Base1: Sendable, Base2: Sendable,
@@ -30,6 +33,7 @@ public struct AsyncCombineLatest2Sequence<Base1: AsyncSequence, Base2: AsyncSequ
 extension AsyncCombineLatest2Sequence: AsyncSequence {
   public typealias Element = (Base1.Element, Base2.Element)
 
+  /// The iterator for a `AsyncCombineLatest2Sequence` instance.
   public struct Iterator: AsyncIteratorProtocol, Sendable {
     enum Partial: Sendable {
       case first(Result<Base1.Element?, Error>, Base1.AsyncIterator)

Sources/AsyncAlgorithms/AsyncCombineLatest3Sequence.swift

@@ -9,10 +9,13 @@
 //
 //===----------------------------------------------------------------------===//
 
+/// Creates an asynchronous sequence that combines the latest values from three `AsyncSequence` types
+/// by emitting a tuple of the values.
 public func combineLatest<Base1: AsyncSequence, Base2: AsyncSequence, Base3: AsyncSequence>(_ base1: Base1, _ base2: Base2, _ base3: Base3) -> AsyncCombineLatest3Sequence<Base1, Base2, Base3> {
   AsyncCombineLatest3Sequence(base1, base2, base3)
 }
 
+/// An `AsyncSequence` that combines the latest values produced from three asynchronous sequences into an asynchronous sequence of tuples.
 public struct AsyncCombineLatest3Sequence<Base1: AsyncSequence, Base2: AsyncSequence, Base3: AsyncSequence>: Sendable
   where
     Base1: Sendable, Base2: Sendable, Base3: Sendable,
@@ -32,6 +35,7 @@ public struct AsyncCombineLatest3Sequence<Base1: AsyncSequence, Base2: AsyncSequ
 extension AsyncCombineLatest3Sequence: AsyncSequence {
   public typealias Element = (Base1.Element, Base2.Element, Base3.Element)
 
+  /// The iterator for a `AsyncCombineLatest3Sequence` instance.
   public struct Iterator: AsyncIteratorProtocol, Sendable {
     var iterator: AsyncCombineLatest2Sequence<AsyncCombineLatest2Sequence<Base1, Base2>, Base3>.Iterator