Fix the markup

Author: alexeyzimarev

docs/README.md

@@ -27,6 +27,6 @@ RestSharp is probably the most popular HTTP client library for .NET. Featuring a
 RestSharp passed over 165 million downloads on NuGet, with average daily download count close to 42,000. It's being used by many popular OSS projects, including Roslyn and Swagger.
 
 Supported by [AWS](https://aws.amazon.com/developer/language/net/solutions/).
-<div style="text-align: center;">[![AWS Logo](/aws_logo.png)](https://aws.amazon.com)</div>
+<div style="text-align: center;"><a href="https://aws.amazon.com"><img src="/aws_logo.png" alt="AWS logo"></a></div>
 
 Supported by the [.NET Foundation](https://dotnetfoundation.org).