Correct a couple of errors noted by Alex Martelli.

Doc/lib/libxmlrpclib.tex

@@ -17,8 +17,8 @@ structured data.  This module supports writing XML-RPC client code; it
 handles all the details of translating between conformable Python
 objects and XML on the wire.
 
-\begin{classdesc}{Server}{\optional{uri\optional{, transport\optional{,
-                          encoding\optional{, verbose}}}}}
+\begin{classdesc}{Server}{uri\optional{, transport\optional{,
+                          encoding\optional{, verbose}}}}
 A \class{Server} instance is a server proxy that manages communication
 with a remote XML-RPC server.  The required first argument is a URI
 (Uniform Resource Indicator), and will normally be the URL of the
@@ -91,7 +91,7 @@ This method returns a list of strings, one for each (non-system)
 method supported by the XML-RPC server.
 \end{methoddesc}
 
-\begin{methoddesc}{system.methodHelp}{name}
+\begin{methoddesc}{system.methodSignature}{name}
 This method takes one parameter, the name of a method implemented by
 the XML-RPC server.It returns an array of possible signatures for this
 method. A signature is an array of types. The first of these types is