docs(readme): document custom configuration usage in library API

Update the Python API Usage section in README.md to demonstrate how to
initialize MdrsClient with InMemoryConfig to avoid creating local
config files.

README.md

@@ -213,15 +213,21 @@ You can also use this package as a Python library to programmatically interact w
 ```python
 from mdrsclient.client import MdrsClient
 from mdrsclient.cache import InMemoryCache
+from mdrsclient.config import InMemoryConfig
+
+# 1. Setup in-memory configuration and cache to avoid local state files (e.g., config.ini, cache/*.json)
+config = InMemoryConfig("neurodata")
+config.url = "https://neurodata.riken.jp/api"
 
-# 1. Setup client with an in-memory cache to avoid local `.mdrsclient` state files
 cache = InMemoryCache()
-client = MdrsClient.from_remote("neurodata", cache=cache)
 
-# 2. Login to the remote server
+# 2. Initialize client with custom configuration and cache
+client = MdrsClient.from_remote("neurodata", cache=cache, config=config)
+
+# 3. Login to the remote server
 client.login("username", "password")
 
-# 3. Use service methods
+# 4. Use service methods
 labs = client.get_laboratories()
 metadata = client.metadata("neurodata:/NIU/Repository/")