Add serialization rules section.

docs/getting_started.rst

@@ -3,3 +3,26 @@ Getting Started
 ===============
 
 xxx
+
+
+RPC Serialization Rules
+-----------------------
+
+The following built-in types may be used as parameters or return values in
+remote procedure calls:
+
+* bool
+* dict
+* int
+* list
+* long
+* set
+* str
+* tuple
+* unicode
+
+User-defined types may not be used, except for:
+
+* :py:class:`econtext.core.CallError`
+* :py:class:`econtext.core.Context`
+* :py:class:`econtext.core._Dead`