Update __init__.py

Author: MarkDaoust

google/generativeai/__init__.py

@@ -85,7 +85,7 @@
     All support for the `google.generativeai` package has ended. It will no longer be receiving 
     updates bug fixes. Please see the upgrade instructions in the [README][1]
     
-    1: https://github.com/google-gemini/deprecated-generative-ai-python/blob/main/README.md
+    [1]: https://github.com/google-gemini/deprecated-generative-ai-python/blob/main/README.md
     """,
     FutureWarning,
     stacklevel=2