docs(config): add Returns section to Pinecone.config and AsyncPinecone.config

## Purpose

The `config` property docstrings were missing a `Returns:` section, violating
the documentation convention that requires it for all non-None-returning methods.

## Solution

Added `Returns: :class:`~pinecone._internal.config.PineconeConfig`` section to
both `Pinecone.config` and `AsyncPinecone.config`, consistent with sibling
namespace properties. Preserved the existing `Examples:` section in `_client.py`.

Author: jhamon

pinecone/_client.py

@@ -531,6 +531,10 @@ def create_index_from_backup(
     def config(self) -> PineconeConfig:
         """The resolved configuration for this client.
 
+        Returns:
+            :class:`~pinecone._internal.config.PineconeConfig` containing the
+            resolved API key, host, timeout, and connection settings.
+
         Examples:
 
             >>> cfg = pc.config

pinecone/async_client/pinecone.py

@@ -432,7 +432,12 @@ async def create_index_from_backup(
 
     @property
     def config(self) -> PineconeConfig:
-        """The resolved configuration for this client."""
+        """The resolved configuration for this client.
+
+        Returns:
+            :class:`~pinecone._internal.config.PineconeConfig` containing the
+            resolved API key, host, timeout, and connection settings.
+        """
         return self._config
 
     # ---- Backcompat flat-method delegates (:meta private:) ----