HttpClient is not created and managed with IHttpClientFactory

[creyesprog]

MS article on why you should not be managing your HttpClient manually and instead use IHttpClientFactory. See here for line that should be updated.

Important tidbits here:
"Another issue that developers run into is when using a shared instance of HttpClient in long-running processes. In a situation where the HttpClient is instantiated as a singleton or a static object, it fails to handle the DNS changes as described in this issue of the dotnet/runtime GitHub repository."

"Though this class implements IDisposable, declaring and instantiating it within a using statement is not preferred because when the HttpClient object gets disposed of, the underlying socket is not immediately released, which can lead to a socket exhaustion problem. For more information about this issue, see the blog post You're using HttpClient wrong and it's destabilizing your software."

[matthewelwell]

Thanks @creyesprog - would you be open to creating a PR for this?