Update Alpha Disclaimer (#2611)

Fixes: #2606

README.rst

@@ -30,6 +30,7 @@ Documentation for the latest **stable** version of cirq (what you get if you ``p
 - `Installation <https://cirq.readthedocs.io/en/stable/install.html>`_
 - `Documentation <https://cirq.readthedocs.io>`_
 - `Tutorial <https://cirq.readthedocs.io/en/stable/tutorial.html>`_
+- `Cirq-announce email list <https://groups.google.com/forum/#!forum/cirq-announce>`_
 
 
 
@@ -95,9 +96,9 @@ Alpha Disclaimer
 ----------------
 
 **Cirq is currently in alpha.**
-We are still making breaking changes.
-We *will* break your code when we make new releases.
-We recommend that you target a specific version of Cirq, and periodically bump to the latest release.
-That way you have control over when a breaking change affects you.
+We may change or remove parts of Cirq's API when making new releases.
+To be informed of deprecations and breaking changes, subscribe to the
+`cirq-announce google group mailing list <https://groups.google.com/forum/#!forum/cirq-announce>`__.
+
 
 Cirq is not an official Google product. Copyright 2019 The Cirq Developers

docs/index.rst

@@ -14,10 +14,9 @@ Alpha Disclaimer
 ----------------
 
 **Cirq is currently in alpha.**
-We are still making breaking changes.
-We *will* break your code when we make new releases.
-We recommend that you target a specific version of Cirq, and periodically bump to the latest release.
-That way you have control over when a breaking change affects you.
+We may change or remove parts of Cirq's API when making new releases.
+To be informed of deprecations and breaking changes, subscribe to the
+`cirq-announce google group mailing list <https://groups.google.com/forum/#!forum/cirq-announce>`__.
 
 User Documentation
 ------------------

docs/install.md

@@ -14,10 +14,9 @@ If you want to create a development environment, see [development.md](developmen
 ### Alpha Disclaimer
 
 **Cirq is currently in alpha.**
-We are still making breaking changes.
-We *will* break your code when we make new releases.
-We recommend that you target a specific version of Cirq, and periodically bump to the latest release.
-That way you have control over when a breaking change affects you.
+We may change or remove parts of Cirq's API when making new releases.
+To be informed of deprecations and breaking changes, subscribe to the
+[cirq-announce google group mailing list](https://groups.google.com/forum/#!forum/cirq-announce).
 
 ### Installing on Linux