minor documentation updates

examples/chat/README

 
 This example is a simple instant messaging implementation. There are multiple
 partipants in the chat, both sending and reading messages. The sending
-application 'prompt' is separated from the application displayinf the chat
+application 'prompt' is separated from the application displaying the chat
 'display' so that there's no need for sophisticated GUI.
 
 To run the example you'll need both applications plus the 'forwarder' device
@@ -12,7 +12,7 @@ $ ./configure --with-chat --with-forwarder
 $ make
 $ sudo make install
 
-Once it is build create the configuration file (say config.xml) for the
+Once it is built create the configuration file (say config.xml) for the
 forwarder describing which network endpoints are to be used for incoming and
 outgoing messages:
 

src/encoder.hpp

@@ -24,8 +24,6 @@
 #include <string.h>
 #include <algorithm>
 
-#include <stdio.h>
-
 namespace zmq
 {
 
@@ -42,10 +40,12 @@ namespace zmq
         }
 
         //  The function tries to fill the supplied chunk by binary data.
-        //  Returns the size of data actually filled in. If offset is not
-        //  NULL, it is filled by offset of the first message in the batch.
-        //  If there's no beginning of a message in the batch, offset is
-        //  set to -1.
+        //  If offset is not NULL, it is filled by offset of the first message
+        //  in the batch. If there's no beginning of a message in the batch,
+        //  offset is set to -1. Both data_ and size_ are in/out parameters.
+        //  Upon exit, data_ contains actual position of the data read (may
+        //  be different from the position requested) and size_ contains number
+        //  of bytes actually provided.
         inline void read (unsigned char **data_, size_t *size_,
             int *offset_ = NULL)
         {