[Docs] Add State Context Key How-to (#920)

docs/_scripts/copy_notebooks.py

@@ -15,6 +15,7 @@ cloud_sdk_dir = docs_dir / "cloud"
 
 _MANUAL = {
     "how-tos": [
+        "state-context-key.ipynb",
         "async.ipynb",
         "stream-values.ipynb",
         "stream-updates.ipynb",
@@ -88,7 +89,6 @@ _HIDE = set(
         "learning.ipynb",
         "docs/quickstart.ipynb",
         "tutorials/rag-agent-testing.ipynb",
-        "state-context-key.ipynb",
         "time-travel.ipynb",
         "code_assistant/langgraph_code_assistant_mistral.ipynb",
     ]