docs: Fix missing self argument in _get_docs_with_query method of `Cust… (#26312)

…omSelfQueryRetriever`

This commit corrects an issue in the `_get_docs_with_query` method of
the `CustomSelfQueryRetriever` class. The method was incorrectly using
`self.vectorstore.similarity_search_with_score(query, **search_kwargs)`
without including the `self` argument, which is required for proper
method invocation.

The `self` argument is necessary for calling instance methods and
accessing instance attributes. By including `self` in the method call,
we ensure that the method is correctly executed in the context of the
current instance, allowing it to function as intended.

No other changes were made to the method's logic or functionality.

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Co-authored-by: Erick Friis <erick@langchain.dev>

docs/docs/how_to/add_scores_retriever.ipynb

@@ -206,7 +206,7 @@
     "    ) -> List[Document]:\n",
     "        \"\"\"Get docs, adding score information.\"\"\"\n",
     "        docs, scores = zip(\n",
-    "            *vectorstore.similarity_search_with_score(query, **search_kwargs)\n",
+    "            *self.vectorstore.similarity_search_with_score(query, **search_kwargs)\n",
     "        )\n",
     "        for doc, score in zip(docs, scores):\n",
     "            doc.metadata[\"score\"] = score\n",