Update comments. Explain that zrpc is an internal detail of ZEO.

src/ZEO/zrpc/__init__.py

@@ -12,9 +12,13 @@
 #
 ##############################################################################
 # zrpc is a package with the following modules
+# client -- manages connection creation to remote server
+# connection -- object dispatcher
+# log -- logging helper
 # error -- exceptions raised by zrpc
 # marshal -- internal, handles basic protocol issues
-# connection -- object dispatcher
-# client -- manages connection creation to remote server
 # server -- manages incoming connections from remote clients
+# smac -- sized message async connections
 # trigger -- medusa's trigger
+
+# zrpc is not an advertised subpackage of ZEO; its interfaces are internal