Update configuration.mdx based on issue #266

Author: kgowru

fern/products/sdks/overview/python/configuration.mdx

@@ -21,13 +21,15 @@ groups:
 ## SDK Configuration Options
 
 <ParamField path="additional_init_exports" type="array" default="null" required={false} toc={true}>
+  Additional exports to include in the package's __init__.py file.
 </ParamField>
 
 <ParamField path="default_bytes_stream_chunk_size" type="number" default="null" required={false} toc={true}>
   The chunk size to use (if any) when processing a response bytes stream within `iter_bytes` or `aiter_bytes` results in: `for chunk in response.iter_bytes(chunk_size=<default_bytes_stream_chunk_size>):`
 </ParamField>
 
 <ParamField path="exclude_types_from_init_exports" type="bool" default="false" required={false} toc={true}>
+  Whether to exclude type definitions from being exported in the package's __init__.py file.
 </ParamField>
 
 <ParamField path="extra_dependencies" type="object" default="{}" required={false} toc={true}>
@@ -40,98 +42,83 @@ groups:
 </ParamField>
 
 <ParamField path="extra_dev_dependencies" type="object" default="{}" required={false} toc={true}>
+  Additional development dependencies to include in the generated package.
 </ParamField>
 
 <ParamField path="extras" type="object" default="{}" required={false} toc={true}>
+  Optional dependency groups that can be installed with the package.
 </ParamField>
 
 <ParamField path="flat_layout" type="bool" default="false" required={false} toc={true}>
+  Whether to generate a flat file structure instead of nested directories.
 </ParamField>
 
 <ParamField path="follow_redirects_by_default" type="bool" default="true" required={false} toc={true}>
   Whether to follow redirects by default in HTTP requests.
 </ParamField>
 
 <ParamField path="improved_imports" type="bool" default="true" required={false} toc={true}>
-  Feature flag that improves imports in the Python SDK by removing nested `resources` directory
+  Feature flag that improves imports in the Python SDK by removing nested `resources` directory.
 </ParamField>
 
 <ParamField path="include_legacy_wire_tests" type="bool" default="false" required={false} toc={true}>
-  Whether or not to include legacy wire tests in the generated SDK
+  Whether or not to include legacy wire tests in the generated SDK.
 </ParamField>
 
 <ParamField path="include_union_utils" type="bool" default="false" required={false} toc={true}>
+  When enabled, generates utility functions for working with union types.
 </ParamField>
 
 <ParamField path="inline_path_params" type="bool" default="false" required={false} toc={true}>
-  If true, treats path parameters as named parameters in endpoint functions.
+  If true, treats path parameters as named parameters in endpoint functions rather than using a request object.
 </ParamField>
 
 <ParamField path="inline_request_params" type="bool" default="true" required={false} toc={true}>
   Feature flag that removes the usage of request objects, and instead uses parameters in function signatures where possible.
 </ParamField>
 
 <ParamField path="package_name" type="string" default="null" required={false} toc={true}>
-
-Specifies the Python package name that users will import your generated client
-from.
+  Specifies the Python package name that users will import your generated client from.
 
-For example, setting `package_name: "my_custom_package"` enables users to use
-`my_custom_package import Client` to import your client:
+  For example, setting `package_name: "my_custom_package"` enables users to use `my_custom_package import Client` to import your client:
 
-```yaml {7-10}
-default-group: local
-groups:
-  local:
-    generators:
-      - name: fernapi/fern-python
-        version: 0.7.1
-        config:
-          package_name: "my_custom_package"
-```
+  ```yaml
+  config:
+    package_name: "my_custom_package"
+  ```
 </ParamField>
 
 <ParamField path="pydantic_config" type="SdkPydanticModelCustomConfig" default="SdkPydanticModelCustomConfig()" required={false} toc={true}>
+  Configuration options for Pydantic model generation.
 </ParamField>
 
 <ParamField path="pydantic_config.include_union_utils" type="bool" default="false" required={false} toc={true}>
-  When enabled, the generator will output a Pydantic `__root__` class that will contain utilities to visit the union. For example, for the following union type:
+  When enabled, generates a Pydantic `__root__` class containing utilities to visit unions. For example:
 
-  ```
-  types:
-  Shape:
-    union:
-      circle: Circle
-      triangle: Triangle
-  ```
-  you will get a generated `Shape` class that has a factory and visitor:
   ```python
   # Use a factory to instantiate the union
   Shape.factory.circle(Circle(...))
   
   # Visit every case in the union
   shape = get_shape()
   shape.visit(
-    circle: lambda circle: do_something_with_circle(circle),
-    triangle: lambda triangle: do_something_with_triangle(triangle),
+    circle=lambda circle: do_something_with_circle(circle),
+    triangle=lambda triangle: do_something_with_triangle(triangle),
   )
   ```
-
-  When enabled, the python generator will not run Black formatting in the generated code. Black is slow so this can potentially speed up code generation quite a bit.
 </ParamField>
 
 <ParamField path="pydantic_config.version" type="'v1' | 'v2' | 'both' | 'v1_on_v2'" default="both" required={false} toc={true}>
-  By default, the generator generates pydantic models that are v1 and v2 compatible. However you can override them to:
+  Controls Pydantic version compatibility:
   - `v1`: strictly use Pydantic v1
-  - `v2`: strictly use Pydantic v2
+  - `v2`: strictly use Pydantic v2 
   - `both`: maintain compatibility with both versions
   - `v1_on_v2`: use Pydantic v1 compatibility layer on v2
-  
-  Example:
+
   ```yaml
   config:
     pydantic_config:
-      version: v1 # or v2 or "both"
+      version: v2
   ```
 </ParamField>
 
@@ -140,20 +127,23 @@ groups:
 </ParamField>
 
 <ParamField path="pyproject_toml" type="string" default="null" required={false} toc={true}>
+  Custom pyproject.toml contents to include in the generated package.
 </ParamField>
 
 <ParamField path="should_generate_websocket_clients" type="bool" default="false" required={false} toc={true}>
   Feature flag that enables generation of Python websocket clients.
 </ParamField>
 
 <ParamField path="skip_formatting" type="bool" default="false" required={false} toc={true}>
+  Whether to skip code formatting on the generated files.
 </ParamField>
 
 <ParamField path="timeout_in_seconds" type="number | 'infinity'" default="60" required={false} toc={true}>
   By default, the generator generates a client that times out after 60 seconds. You can customize this value by providing a different number or setting to `infinity` to get rid of timeouts.
 </ParamField>
 
 <ParamField path="use_api_name_in_package" type="bool" default="false" required={false} toc={true}>
+  Whether to include the API name in the generated package name.
 </ParamField>
 
 <ParamField path="use_inheritance_for_extended_models" type="bool" default="true" required={false} toc={true}>
@@ -168,17 +158,48 @@ groups:
   Whether or not to generate TypedDicts instead of Pydantic Models for file upload request objects. Note that this flag was only introduced due to an oversight in the `use_typeddict_requests` flag implementation; it should be removed in the future.
 </ParamField>
 
+### Extension Headers
+
+The Python generator supports extension headers through the `x-fern-sdk-variables` configuration in your OpenAPI spec. This allows you to define variables that will be included in the client configuration and injected into API paths.
+
+For example, to define a project ID variable that will be included in all paths:
+
+```yaml
+x-fern-sdk-variables:
+  project_id:
+    type: string
+    description: "The ID of the project"
+    pattern: "^proj_[a-zA-Z0-9]+$"
+```
+
+This variable can then be referenced in your paths:
+
+```yaml
+paths:
+  /v1/connect/{project_id}/accounts:
+    parameters:
+      - name: project_id
+        in: path
+        required: true
+        schema:
+          type: string
+        x-fern-sdk-variable: project_id
+```
+
+The generated client will include this variable in its configuration and automatically inject it into request paths.
+
 ### client
-  Configuration for the generated client class and file structure.
 
-  ```yaml
-  config:
-    client:
-      filename: "my_client.py"
-      class_name: "MyClient"
-      exported_filename: "my_client.py"
-      exported_class_name: "MyClient"
-  ```
+Configuration for the generated client class and file structure.
+
+```yaml
+config:
+  client:
+    filename: "my_client.py"
+    class_name: "MyClient"
+    exported_filename: "my_client.py" 
+    exported_class_name: "MyClient"
+```
 
 <ParamField path="filename" type="string" default="client.py" required={false} toc={true}>
   The filename for the generated client file.