Add deprecation banner to Motor docs (#1007)

Author: jordan-smith721

snooty.toml

@@ -20,3 +20,15 @@ stable-api = "Stable API"
 node-driver-long = "MongoDB Node.js Driver"
 node-driver-short = "Node.js Driver"
 atlas = "MongoDB Atlas"
+
+[[banners]]
+targets = ["motor.txt"]
+variant = "warning"
+value = """
+    As of May 14th, 2025, Motor has been sunset in favor of the GA release of the PyMongo Async API in Pymongo. \
+    No new features will be added to Motor. Motor will be deprecated on May 14th, 2026, \
+    and no further bug fixes will be released after deprecation, with the exception of critical bug fixes, which will be released until May 14th, 2027. \
+    We strongly recommend that Motor users migrate to PyMongo Async while Motor is still supported. \
+    To learn how to migrate from Motor to the PyMongo Async API, see the \
+    `Migrate to PyMongo Async guide <https://www.mongodb.com/docs/languages/python/pymongo-driver/current/reference/migration/>`__.
+    """