Fix some markup nits

Doc/lib/libfuncs.tex

@@ -91,8 +91,8 @@ def my_import(name):
 \indexii{Boolean}{type}
 \versionadded{2.2.1}
 
-  If no argument is given, this function returns \code{False}.
-  \versionchanged{2.3}
+  \versionchanged[If no argument is given, this function returns 
+                  \code{False}]{2.3}
 \end{funcdesc}
 
 \begin{funcdesc}{buffer}{object\optional{, offset\optional{, size}}}
@@ -687,8 +687,8 @@ for all new style classes.  It has the methods that are common
 to all instances of new style classes.
 \versionadded{2.2}
 
-This function does not accept any arguments.  \versionchanged{2.3}
-Formerly, it accepted arguments but ignored them.
+\versionchanged[This function does not accept any arguments.
+Formerly, it accepted arguments but ignored them]{2.3}
 \end{funcdesc}
 
 \begin{funcdesc}{oct}{x}