Use a link that passes markdown link validation

Author: eiriktsarpalis

docs/index.md

@@ -4,7 +4,7 @@ _layout: landing
 
 # Overview
 
-The official C# SDK for the [Model Context Protocol](https://modelcontextprotocol.io/), enabling .NET applications, services, and libraries to implement and interact with MCP clients and servers. Please visit our [API documentation](api/ModelContextProtocol.yml) for more details on available functionality.
+The official C# SDK for the [Model Context Protocol](https://modelcontextprotocol.io/), enabling .NET applications, services, and libraries to implement and interact with MCP clients and servers. Please visit our [API documentation](https://modelcontextprotocol.github.io/csharp-sdk/api/ModelContextProtocol.html) for more details on available functionality.
 
 ## About MCP