fix(examples): add servers in examples's readme (#229)

Signed-off-by: jokemanfire <hu.dingyang@zte.com.cn>

examples/servers/src/memory_stdio.rs

@@ -0,0 +1,18 @@
+use std::error::Error;
+mod common;
+use common::generic_service::{GenericService, MemoryDataService};
+use rmcp::serve_server;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn Error>> {
+    let memory_service = MemoryDataService::new("initial data");
+
+    let generic_service = GenericService::new(memory_service);
+
+    println!("start server, connect to standard input/output");
+
+    let io = (tokio::io::stdin(), tokio::io::stdout());
+
+    serve_server(generic_service, io).await?;
+    Ok(())
+}