bpo-23554: Change echo server example class name from EchoServerClientProtocol to EchoServerProtocol (GH-9859)

Doc/library/asyncio-protocol.rst

@@ -717,7 +717,7 @@ received data, and close the connection::
     import asyncio
 
 
-    class EchoServerClientProtocol(asyncio.Protocol):
+    class EchoServerProtocol(asyncio.Protocol):
         def connection_made(self, transport):
             peername = transport.get_extra_info('peername')
             print('Connection from {}'.format(peername))
@@ -740,7 +740,7 @@ received data, and close the connection::
         loop = asyncio.get_running_loop()
 
         server = await loop.create_server(
-            lambda: EchoServerClientProtocol(),
+            lambda: EchoServerProtocol(),
             '127.0.0.1', 8888)
 
         async with server: