SF bug: 751941 Invisible HTML tag

Added missing jump target labels.

Doc/lib/libfuncs.tex

@@ -119,6 +119,7 @@ def my_import(name):
 \end{funcdesc}
 
 \begin{funcdesc}{classmethod}{function}
+  \label{classmethod}
   Return a class method for \var{function}.
 
   A class method receives the class as implicit first argument,
@@ -883,6 +884,7 @@ class C(object):
 \end{funcdesc}
 
 \begin{funcdesc}{staticmethod}{function}
+  \label{staticmethod}
   Return a static method for \var{function}.
 
   A static method does not receive an implicit first argument.