Update README.md

Added DKIM Support to README.md

README.md

@@ -9,7 +9,6 @@ SPDX-License-Identifier: CC0-1.0
 [![GoDoc](https://godoc.org/github.com/wneessen/go-mail?status.svg)](https://pkg.go.dev/github.com/wneessen/go-mail)
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-[![Build Status](https://api.cirrus-ci.com/github/wneessen/go-mail.svg)](https://cirrus-ci.com/github/wneessen/go-mail) 
 [![Mentioned in Awesome Go](https://awesome.re/mentioned-badge-flat.svg)](https://github.com/avelino/awesome-go) [![#go-mail on Discord](https://img.shields.io/badge/Discord-%23gomail-blue.svg)](https://discord.gg/zSUeBrsFPB) 
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 <a href="https://ko-fi.com/D1D24V9IX"><img src="https://uploads-ssl.webflow.com/5c14e387dab576fe667689cf/5cbed8a4ae2b88347c06c923_BuyMeACoffee_blue.png" height="20" alt="buy ma a coffee"></a>
@@ -45,6 +44,7 @@ Some of the features of this library:
 * [X] Middleware support for 3rd-party libraries to alter mail messages
 * [X] Support sending mails via a local sendmail command
 * [X] Support for requestng MDNs (RFC 8098) and DSNs (RFC 1891)
+* [X] DKIM signature support via [go-mail-middlware](https://github.com/wneessen/go-mail-middleware)
 * [X] Message object satisfies `io.WriteTo` and `io.Reader` interfaces
 * [X] Support for Go's `html/template` and `text/template` (as message body, alternative part or attachment/emebed)
 * [X] Output to file support which allows storing mail messages as e. g. `.eml` files to disk to open them in a MUA