Mix some typos in XML docs (#1458)

src/Polly.Core/ResilienceStrategy.cs

@@ -24,14 +24,15 @@ public abstract partial class ResilienceStrategy
     /// <param name="context">The context associated with the callback.</param>
     /// <param name="state">The state associated with the callback.</param>
     /// <returns>
-    /// An instance of pending <see cref="ValueTask"/> for asynchronous executions or completed <see cref="ValueTask"/> task for synchronous exexutions.
+    /// An instance of pending <see cref="ValueTask"/> for asynchronous executions or completed <see cref="ValueTask"/> task for synchronous executions.
     /// </returns>
     /// <remarks>
     /// <strong>This method is called for both synchronous and asynchronous execution flows.</strong>
     /// <para>
-    /// You can use <see cref="ResilienceContext.IsSynchronous"/> to dermine wheether the <paramref name="callback"/> is synchronous or asynchronous one.
+    /// You can use <see cref="ResilienceContext.IsSynchronous"/> to determine whether the <paramref name="callback"/> is synchronous or asynchronous one.
     /// This is useful when the custom strategy behaves differently in each execution flow. In general, for most strategies, the implementation
     /// is the same for both execution flows.
+    /// See <seealso href="https://github.com/App-vNext/Polly/blob/main/src/Polly.Core/README.md#about-synchronous-and-asynchronous-executions"/> for more details.
     /// </para>
     /// <para>
     /// The provided callback never throws an exception. Instead, the exception is captured and converted to an <see cref="Outcome{TResult}"/>.

src/Polly.Core/ResilienceStrategyT.Async.cs

@@ -79,6 +79,7 @@ public ValueTask<TResult> ExecuteAsync<TResult, TState>(
     public ValueTask<TResult> ExecuteAsync<TResult>(
         Func<CancellationToken, ValueTask<TResult>> callback,
         CancellationToken cancellationToken = default)
+        where TResult : T
     {
         Guard.NotNull(callback);