Add guidance on tutorials index page

docs/tutorials.rst

@@ -4,6 +4,12 @@
 Tutorials
 =========
 
+.. note::
+  The Simulators tutorials have moved to
+  `Qiskit Aer <https://qiskit.org/ecosystem/aer/tutorials/index.html>`_
+  and the Algorithms tutorials to
+  `Qiskit Algorithms <https://qiskit.org/ecosystem/algorithms/tutorials/index.html>`_.
+
 Introductory
 ============
 
@@ -32,6 +38,12 @@ Advanced circuits
 Operators
 =========
 
+.. deprecated:: 0.24.0
+   The operators tutorials rely on the ``opflow`` module, which has been deprecated since
+   Qiskit 0.44 (aka Qiskit Terra 0.24). Refer to the
+   `Opflow migration guide <https://qisk.it/opflow_migration>`_.
+   These tutorials will be removed in the future.
+
 .. nbgallery::
    :glob: