docs: replace direct metadata model imports in how-to examples with airflow.sdk

Author: sunank200

airflow-core/docs/core-concepts/variables.rst

@@ -33,6 +33,22 @@ To use them, just import and call ``get`` on the Variable model::
     # Returns the value of default (None) if the variable is not set
     baz = Variable.get("baz", default=None)
 
+.. versionchanged:: 3.0
+
+   In Airflow 3.0+, you can also access variables through the Task Context using
+   :func:`~airflow.sdk.get_current_context`:
+
+   .. code-block:: python
+
+       from airflow.sdk import get_current_context
+
+
+       def my_task():
+           context = get_current_context()
+           var = context["var"]
+           my_variable = var.get("my_variable_name")
+           return my_variable
+
 You can also use them from :ref:`templates <concepts:jinja-templating>`::
 
     # Raw value

airflow-core/docs/howto/connection.rst

@@ -22,7 +22,12 @@ Managing Connections
 
   For an overview of hooks and connections, see :doc:`/authoring-and-scheduling/connections`.
 
-Airflow's :class:`~airflow.models.connection.Connection` object is used for storing credentials and other information necessary for connecting to external services.
+.. versionchanged:: 3.0
+
+   Direct metadata-model access to :class:`~airflow.models.connection.Connection` in task or management code is deprecated.
+   Use the public SDK API (:class:`~airflow.sdk.Connection`), the Stable REST API, or the Python Client instead.
+
+Airflow's :class:`~airflow.sdk.Connection` object is used for storing credentials and other information necessary for connecting to external services.
 
 Connections may be defined in the following ways:
 
@@ -77,7 +82,7 @@ convenience property :py:meth:`~airflow.models.connection.Connection.as_json`. I
 
 .. code-block:: pycon
 
-    >>> from airflow.models.connection import Connection
+    >>> from airflow.sdk import Connection
     >>> c = Connection(
     ...     conn_id="some_conn",
     ...     conn_type="mysql",
@@ -94,7 +99,7 @@ In addition, same approach could be used to convert Connection from URI format t
 
 .. code-block:: pycon
 
-    >>> from airflow.models.connection import Connection
+    >>> from airflow.sdk import Connection
     >>> c = Connection(
     ...     conn_id="awesome_conn",
     ...     description="Example Connection",

airflow-core/docs/howto/custom-operator.rst

@@ -24,7 +24,7 @@ Creating a custom Operator
 Airflow allows you to create new operators to suit the requirements of you or your team.
 This extensibility is one of the many features which make Apache Airflow powerful.
 
-You can create any operator you want by extending the :class:`airflow.models.baseoperator.BaseOperator`
+You can create any operator you want by extending the public SDK base class :class:`~airflow.sdk.BaseOperator`.
 
 There are two methods that you need to override in a derived class: