Add version directives to ast docs

Doc/library/ast.rst

@@ -650,10 +650,10 @@ Expressions
 
 .. class:: NamedExpr(target, value)
 
-    A named expression. This AST node is produced by the assignment expressions
-    operator (also known as the walrus operator). As opposed to the :class:`Assign`
-    node in which the first argument can be multiple nodes, in this case both
-    ``target`` and ``value`` must be single nodes.
+   A named expression. This AST node is produced by the assignment expressions
+   operator (also known as the walrus operator). As opposed to the :class:`Assign`
+   node in which the first argument can be multiple nodes, in this case both
+   ``target`` and ``value`` must be single nodes.
 
    .. doctest::
 
@@ -663,6 +663,7 @@ Expressions
                 target=Name(id='x', ctx=Store()),
                 value=Constant(value=4)))
 
+   .. versionadded:: 3.8
 
 Subscripting
 ~~~~~~~~~~~~
@@ -1036,6 +1037,7 @@ Statements
                     value=Name(id='int', ctx=Load()))],
             type_ignores=[])
 
+   .. versionadded:: 3.12
 
 Other statements which are only applicable inside functions or loops are
 described in other sections.
@@ -1318,6 +1320,7 @@ Control flow
                     finalbody=[])],
             type_ignores=[])
 
+   .. versionadded:: 3.11
 
 .. class:: ExceptHandler(type, name, body)
 
@@ -1407,6 +1410,8 @@ Pattern matching
    that is being matched against the cases) and ``cases`` contains an iterable of
    :class:`match_case` nodes with the different cases.
 
+   .. versionadded:: 3.10
+
 .. class:: match_case(pattern, guard, body)
 
    A single case pattern in a ``match`` statement. ``pattern`` contains the
@@ -1458,6 +1463,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. class:: MatchValue(value)
 
    A match literal or value pattern that compares by equality. ``value`` is
@@ -1485,6 +1492,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. class:: MatchSingleton(value)
 
    A match literal pattern that compares by identity. ``value`` is the
@@ -1510,6 +1519,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. class:: MatchSequence(patterns)
 
    A match sequence pattern. ``patterns`` contains the patterns to be matched
@@ -1541,6 +1552,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. class:: MatchStar(name)
 
    Matches the rest of the sequence in a variable length match sequence pattern.
@@ -1581,6 +1594,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. class:: MatchMapping(keys, patterns, rest)
 
    A match mapping pattern. ``keys`` is a sequence of expression nodes.
@@ -1627,6 +1642,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. class:: MatchClass(cls, patterns, kwd_attrs, kwd_patterns)
 
    A match class pattern. ``cls`` is an expression giving the nominal class to
@@ -1691,6 +1708,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. class:: MatchAs(pattern, name)
 
    A match "as-pattern", capture pattern or wildcard pattern. ``pattern``
@@ -1732,6 +1751,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. class:: MatchOr(patterns)
 
    A match "or-pattern". An or-pattern matches each of its subpatterns in turn
@@ -1764,6 +1785,8 @@ Pattern matching
                                     value=Constant(value=Ellipsis))])])],
             type_ignores=[])
 
+   .. versionadded:: 3.10
+
 .. _ast-type-params:
 
 Type parameters
@@ -1795,6 +1818,8 @@ aliases.
                         ctx=Load()))],
             type_ignores=[])
 
+   .. versionadded:: 3.12
+
 .. class:: ParamSpec(name)
 
    A :class:`typing.ParamSpec`. ``name`` is the name of the parameter specification.
@@ -1818,6 +1843,8 @@ aliases.
                         ctx=Load()))],
             type_ignores=[])
 
+   .. versionadded:: 3.12
+
 .. class:: TypeVarTuple(name)
 
    A :class:`typing.TypeVarTuple`. ``name`` is the name of the type variable tuple.
@@ -1842,6 +1869,8 @@ aliases.
                         ctx=Load()))],
             type_ignores=[])
 
+   .. versionadded:: 3.12
+
 Function and class definitions
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -1861,6 +1890,9 @@ Function and class definitions
 
        ``type_comment`` is an optional string with the type annotation as a comment.
 
+   .. versionchanged:: 3.12
+        Added ``type_params``.
+
 
 .. class:: Lambda(args, body)
 
@@ -2059,6 +2091,9 @@ Function and class definitions
                     type_params=[])],
             type_ignores=[])
 
+   .. versionchanged:: 3.12
+        Added ``type_params``.
+
 Async and await
 ^^^^^^^^^^^^^^^
 
@@ -2067,6 +2102,9 @@ Async and await
    An ``async def`` function definition. Has the same fields as
    :class:`FunctionDef`.
 
+   .. versionchanged:: 3.12
+        Added ``type_params``.
+
 
 .. class:: Await(value)