Update gep-1742.md to add more Nginx's timeout settings

according to the suggestion in kubernetes-sigs#2117 (review)

geps/gep-1742.md

@@ -166,7 +166,10 @@ sequenceDiagram
     C->>P: Finishes Headers
     Note right of P: client_headers_timeout
     deactivate P
+    activate P
     C->>P: Finishes request
+	deactivate P
+	Note right of P: client_body_timeout
     activate U
     note left of U: proxy_connect_timeout<br/>grpc_connect_timeout
     deactivate U
@@ -184,11 +187,14 @@ sequenceDiagram
         Note right of U: (between read operations)<br/>proxy_read_timeout<br/>grpc_read_timeout
     U->>P: Finishes Response
     deactivate U
+	activate P
     P->>C: Starts Response
     P->>C: Finishes Headers
     P->>C: Finishes Response
-    Note right of P: Repeat if connection sharing
-    Note Right of U: keepalive_timeout (if keepalive enabled)
+	deactivate P
+	Note left of P: send_timeout (only between two successive write operations)
+    Note right of P: Repeat if connection is shared until server's keepalive_timeout is hit
+    Note Right of U: upstream's keepalive_timeout (if keepalive enabled)
     U->>C: Connection ended
 		deactivate U
 ```