updated/removed a few versionadded/versionchanged

Doc/library/bdb.rst

@@ -76,7 +76,7 @@ The :mod:`bdb` module also defines two classes:
    frame is considered to originate in a certain module is determined
    by the ``__name__`` in the frame globals.
 
-   .. versionadded:: 2.7
+   .. versionadded:: 3.1
       The *skip* argument.
 
    The following methods of :class:`Bdb` normally don't need to be overridden.

Doc/library/operator.rst

@@ -109,8 +109,6 @@ The mathematical and bitwise operations are the most numerous:
 
    Return *a* converted to an integer.  Equivalent to ``a.__index__()``.
 
-   .. versionadded:: 2.5
-
 
 .. function:: inv(obj)
               invert(obj)

Doc/library/string.rst

@@ -471,8 +471,6 @@ The available presentation types for floating point and decimal values are:
 Template strings
 ----------------
 
-.. versionadded:: 2.4
-
 Templates provide simpler string substitutions as described in :pep:`292`.
 Instead of the normal ``%``\ -based substitutions, Templates support ``$``\
 -based substitutions, using the following rules:

Doc/library/sys.rst

@@ -439,7 +439,7 @@ always available.
 
    Availability: Windows.
 
-   .. versionchanged:: 2.7
+   .. versionchanged:: 3.2
       Changed to a named tuple and added *service_pack_minor*,
       *service_pack_major*, *suite_mask*, and *product_type*.