docs: mention caveats with CacheBackedEmbeddings.embed_query (#19926)

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- **Description:** mention not-caching methods in CacheBackedEmbeddings
  - **Issue:** n/a I almost created one until I read the code 
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docs/docs/modules/data_connection/text_embedding/caching_embeddings.ipynb

@@ -29,7 +29,10 @@
     "- batch_size: (optional, defaults to `None`) The number of documents to embed between store updates.\n",
     "- namespace: (optional, defaults to `\"\"`) The namespace to use for document cache. This namespace is used to avoid collisions with other caches. For example, set it to the name of the embedding model used.\n",
     "\n",
-    "**Attention**: Be sure to set the `namespace` parameter to avoid collisions of the same text embedded using different embeddings models."
+    "**Attention**:\n",
+    "\n",
+    "- Be sure to set the `namespace` parameter to avoid collisions of the same text embedded using different embeddings models.\n",
+    "- Currently `CacheBackedEmbeddings` does not cache embedding created with `embed_query()` `aembed_query()` methods."
    ]
   },
   {