Docs: Update FilterRetriever docstrings (#8133)

* update docstrings

* Update haystack/components/retrievers/filter_retriever.py

Co-authored-by: Daria Fokina <[email protected]>

---------

Co-authored-by: Daria Fokina <[email protected]>

Author: agnieszka-m

haystack/components/retrievers/filter_retriever.py

@@ -16,7 +16,8 @@ class FilterRetriever:
     """
     Retrieves documents that match the provided filters.
 
-    Usage example:
+    ### Usage example
+
     ```python
     from haystack import Document
     from haystack.components.retrievers import FilterRetriever
@@ -31,7 +32,7 @@ class FilterRetriever:
     doc_store.write_documents(docs)
     retriever = FilterRetriever(doc_store, filters={"field": "lang", "operator": "==", "value": "en"})
 
-    # if passed in the run method, filters will override those provided at initialization
+    # if passed in the run method, filters override those provided at initialization
     result = retriever.run(filters={"field": "lang", "operator": "==", "value": "de"})
 
     print(result["documents"])
@@ -43,7 +44,7 @@ def __init__(self, document_store: DocumentStore, filters: Optional[Dict[str, An
         Create the FilterRetriever component.
 
         :param document_store:
-            An instance of a DocumentStore.
+            An instance of a Document Store to use with the Retriever.
         :param filters:
             A dictionary with filters to narrow down the search space.
         """
@@ -98,8 +99,8 @@ def run(self, filters: Optional[Dict[str, Any]] = None):
 
         :param filters:
             A dictionary with filters to narrow down the search space.
-            If not specified, the FilterRetriever uses the value provided at initialization.
+            If not specified, the FilterRetriever uses the values provided at initialization.
         :returns:
-            The retrieved documents.
+            A list of retrieved documents.
         """
         return {"documents": self.document_store.filter_documents(filters=filters or self.filters)}