Add README for the InMemoryTransport sample

Documents the sample's purpose, how to run it, the expected output, and
notes on the pipe wiring, following the style of the TasksExtension and
WeatherAppServer sample READMEs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: Akbar Dızajı

samples/InMemoryTransport/README.md

@@ -0,0 +1,42 @@
+# In-Memory Transport Sample
+
+Demonstrates connecting an MCP client and server in the same process using stream-based
+transports over in-memory pipes (`System.IO.Pipelines`) — no child process, no network.
+
+The server is created directly with `McpServer.Create`, without a host or dependency
+injection container, and exposes a single `Echo` tool defined from a delegate with
+`McpServerTool.Create`. The client connects over the same pipe pair with
+`StreamClientTransport`, lists the server's tools, and invokes the tool.
+
+This pattern is useful for testing MCP servers, embedding a server inside a larger
+application, or running a client and server in the same process without transport overhead.
+See [Transports: In-memory transport](../../docs/concepts/transports/transports.md) for more
+background.
+
+## Run
+
+```bash
+dotnet run --project samples/InMemoryTransport/InMemoryTransport.csproj
+```
+
+Expected output:
+
+```
+Tool Name: Echo
+
+Echo: Hello World
+```
+
+## Key files
+
+- [`Program.cs`](Program.cs) — the entire sample: pipe setup, server creation, client
+  connection, tool listing, and tool invocation.
+
+## Notes
+
+- `StreamServerTransport` and `StreamClientTransport` work with any `Stream`. This sample
+  wires them to a pair of `Pipe` instances, one per direction; the client's output stream is
+  the server's input stream and vice versa.
+- The server is started with a fire-and-forget `server.RunAsync()` because both endpoints
+  live in the same process. `await using` on the server and client ensures both are disposed
+  when the program exits.