Add examples of configurable headers (#4445)

docs/docs/cloud/how-tos/configurable_headers.md

@@ -17,8 +17,58 @@ Here's how to customize the included and excluded headers:
 }
 ```
 
+
 The `include` and `exclude` lists accept exact header names or patterns using `*` to match any number of characters. For your security, no other regex patterns are supported.
 
+## Using within your graph
+
+You can access the included headers in your graph using the `config` argument of any node.
+
+```python
+def my_node(state, config):
+  organization_id = config["configurable"].get("x-organization-id")
+  ...
+```
+
+Or by fetching from context (useful in tools and or within other nested functions).
+
+```python
+from langgraph.config import get_config
+
+def search_everything(query: str):
+  organization_id = get_config()["configurable"].get("x-organization-id")
+  ...
+```
+
+
+You can even use this to dynamically compile the graph.
+
+```python
+# my_graph.py.
+import contextlib
+
+@contextlib.asynccontextmanager
+async def generate_agent(config):
+  organization_id = config["configurable"].get("x-organization-id")
+  if organization_id == "org1":
+    graph = ...
+    yield graph
+  else:
+    graph = ...
+    yield graph
+
+```
+
+```json
+{
+  "graphs": {"agent": "my_grph.py:generate_agent"}
+}
+```
+
+For more examples on how to use runtime configuration, check out the [configuration how-to](../../how-tos/configuration.ipynb).
+
+### Opt-out of configurable headers
+
 If you'd like to opt-out of configurable headers, you can simply set a wildcard pattern in the `exclude` list:
 
 ```json