Add Swift SDK Tier 3 assessment to SDK listing (modelcontextprotocol#2310)

Co-authored-by: Felix Weinberger <3823880+felixweinberger@users.noreply.github.com>

Author: movetz

docs/docs/sdk.mdx

@@ -15,7 +15,7 @@ Build MCP servers and clients using our official SDKs. SDKs are classified into
 | <Icon icon="square-c" size={24} /> &nbsp; C#          | [modelcontextprotocol/csharp-sdk](https://github.com/modelcontextprotocol/csharp-sdk)         | [Tier 1](https://github.com/modelcontextprotocol/modelcontextprotocol/issues/2261) |
 | <Icon icon="golang" size={24} /> &nbsp; Go            | [modelcontextprotocol/go-sdk](https://github.com/modelcontextprotocol/go-sdk)                 |                                                                                TBD |
 | <Icon icon="square-k" size={24} /> &nbsp; Kotlin      | [modelcontextprotocol/kotlin-sdk](https://github.com/modelcontextprotocol/kotlin-sdk)         |                                                                                TBD |
-| <Icon icon="swift" size={24} /> &nbsp; Swift          | [modelcontextprotocol/swift-sdk](https://github.com/modelcontextprotocol/swift-sdk)           |                                                                                TBD |
+| <Icon icon="swift" size={24} /> &nbsp; Swift          | [modelcontextprotocol/swift-sdk](https://github.com/modelcontextprotocol/swift-sdk)           | [Tier 3](https://github.com/modelcontextprotocol/modelcontextprotocol/issues/2309) |
 | <Icon icon="rust" size={24} /> &nbsp; Rust            | [modelcontextprotocol/rust-sdk](https://github.com/modelcontextprotocol/rust-sdk)             |                                                                                TBD |
 | <Icon icon="gem" size={24} /> &nbsp; Ruby             | [modelcontextprotocol/ruby-sdk](https://github.com/modelcontextprotocol/ruby-sdk)             |                                                                                TBD |
 | <Icon icon="php" size={24} /> &nbsp; PHP              | [modelcontextprotocol/php-sdk](https://github.com/modelcontextprotocol/php-sdk)               | [Tier 3](https://github.com/modelcontextprotocol/modelcontextprotocol/issues/2305) |