basic_parser::put doc

fix #494

CHANGELOG.md

@@ -7,6 +7,7 @@ Version 58:
 * Avoid `std::string` in websocket
 * Fix basic_fields insert ordering
 * basic_fields::set optimization
+* basic_parser::put doc
 
 API Changes:
 

include/beast/http/basic_parser.hpp

@@ -323,7 +323,11 @@ public:
         the parser may not be restarted.
 
         @param buffers An object meeting the requirements of
-        @b ConstBufferSequence that represents the message.
+        @b ConstBufferSequence that represents the next chunk of
+        message data. If the length of this buffer sequence is
+        one, the implementation will not allocate additional memory.
+        The class @ref flat_buffer is provided as one way to
+        meet this requirement
 
         @param ec Set to the error, if any occurred.