Update the documentation to reflect the changes to ReferenceError.
diff --git a/Doc/lib/libexcs.tex b/Doc/lib/libexcs.tex
index 5571086..08defcc 100644
--- a/Doc/lib/libexcs.tex
+++ b/Doc/lib/libexcs.tex
@@ -237,6 +237,17 @@
typical applications prefer to drop bits than raise an exception.
\end{excdesc}
+\begin{excdesc}{ReferenceError}
+ This exception is raised when a weak reference proxy, created by the
+ \function{\refmodule{weakref}.proxy()} function, is used to access
+ an attribute of the referent after it has been garbage collected.
+ For more information on weak references, see the \refmodule{weakref}
+ module.
+ \versionadded[Previously known as the
+ \exception{\refmodule{weakref}.ReferenceError}
+ exception]{2.2}
+\end{excdesc}
+
\begin{excdesc}{RuntimeError}
Raised when an error is detected that doesn't fall in any of the
other categories. The associated value is a string indicating what