Correct placement of doc comments in AsyncSequence

Also remove stray characters in doc comments for Actor, MainActor.

Author: Chris Adamson

stdlib/public/Concurrency/Actor.swift

@@ -15,7 +15,7 @@ import Swift
 
 /// Common protocol to which all actors conform.
 ///
-/// The \c Actor protocol generalizes over all actor types. Actor types
+/// The Actor protocol generalizes over all actor types. Actor types
 /// implicitly conform to this protocol.
 @available(SwiftStdlib 5.5, *)
 public protocol Actor: AnyObject, Sendable {
@@ -53,7 +53,7 @@ public func _defaultActorDestroy(_ actor: AnyObject)
 internal func _enqueueOnMain(_ job: UnownedJob)
 
 /// A singleton actor whose executor is equivalent to 
-/// \c DispatchQueue.main, which is the main dispatch queue.
+/// DispatchQueue.main, which is the main dispatch queue.
 @available(SwiftStdlib 5.5, *)
 @globalActor public final actor MainActor: SerialExecutor {
   public static let shared = MainActor()

stdlib/public/Concurrency/AsyncSequence.swift

@@ -74,14 +74,15 @@ import Swift
 @available(SwiftStdlib 5.5, *)
 @rethrows
 public protocol AsyncSequence {
-  /// The type of element produced by this asynchronous sequence.
+    /// The type of asynchronous iterator produced by this asynchronous sequence.
   associatedtype AsyncIterator: AsyncIteratorProtocol where AsyncIterator.Element == Element
-  /// Creates the asynchronous iterator that produces elements of this
-  /// asynchronous sequence.
-  ///
-  /// - Returns: An instance of the `AsyncIterator` type used to produce
-  /// elements of the asynchronous sequence.
+    /// The type of element produced by this asynchronous sequence.
   associatedtype Element
+    /// Creates the asynchronous iterator that produces elements of this
+    /// asynchronous sequence.
+    ///
+    /// - Returns: An instance of the `AsyncIterator` type used to produce
+    /// elements of the asynchronous sequence.
   __consuming func makeAsyncIterator() -> AsyncIterator
 }