Fix parameter description in GetAuthenticatorKeyAsync (#57834)

* Fix parameter description in GetAuthenticatorKeyAsync

Corrected the parameter description for the `user` parameter in the
`GetAuthenticatorKeyAsync` method of the `IUserAuthenticatorKeyStore<TUser>`
interface. The previous description incorrectly referred to the security
stamp, while the new description accurately refers to the authenticator key.

* Update src/Identity/Extensions.Core/src/IUserAuthenticatorKeyStore.cs

Co-authored-by: Martin Costello <martin@martincostello.com>

---------

Co-authored-by: Martin Costello <martin@martincostello.com>

src/Identity/Extensions.Core/src/IUserAuthenticatorKeyStore.cs

@@ -24,7 +24,7 @@ public interface IUserAuthenticatorKeyStore<TUser> : IUserStore<TUser> where TUs
     /// <summary>
     /// Get the authenticator key for the specified <paramref name="user" />.
     /// </summary>
-    /// <param name="user">The user whose security stamp should be set.</param>
+    /// <param name="user">The user whose authenticator key should be retrieved.</param>
     /// <param name="cancellationToken">The <see cref="CancellationToken"/> used to propagate notifications that the operation should be canceled.</param>
     /// <returns>The <see cref="Task"/> that represents the asynchronous operation, containing the security stamp for the specified <paramref name="user"/>.</returns>
     Task<string?> GetAuthenticatorKeyAsync(TUser user, CancellationToken cancellationToken);