Added missing version annotation for dict().

Doc/lib/libfuncs.tex

@@ -201,6 +201,8 @@ def my_import(name):
     \item \code{dict([[2, 3], [1, 2]])}
     \item \code{dict([(i-1, i) for i in (2, 3)])}
   \end{itemize}
+
+  \versionadded{2.2}
 \end{funcdesc}
 
 \begin{funcdesc}{dir}{\optional{object}}