docs: address review comments

Author: srini047

integrations/ollama/src/haystack_integrations/components/embedders/ollama/document_embedder.py

@@ -77,6 +77,9 @@ def __init__(
         self._async_client = AsyncClient(host=self.url, timeout=self.timeout)
 
     def _prepare_input(self, documents: List[Document]) -> List[Document]:
+        """
+        Prepares the list of documents to embed by appropriate validation.
+        """
         if not isinstance(documents, list) or (documents and not isinstance(documents[0], Document)):
             msg = (
                 "OllamaDocumentEmbedder expects a list of Documents as input."