Fix documentation reference to withBatch method

Update doc comment to use correct parameter label `withBatch(body:)`
instead of `withBatch(_:)`.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: jonathanhefner

Sources/MCP/Client/Client.swift

@@ -343,7 +343,7 @@ public actor Client {
     /// A batch of requests.
     ///
     /// Objects of this type are passed as an argument to the closure
-    /// of the ``Client/withBatch(_:)`` method.
+    /// of the ``Client/withBatch(body:)`` method.
     public actor Batch {
         unowned let client: Client
         var requests: [AnyRequest] = []