docs(vectorstores/integrations/chroma): Fix loading and saving (#7437)

- Description: Fix loading and saving code about Chroma
- Issue: the issue #7436 
- Dependencies: -
- Twitter handle: https://twitter.com/ftnext

docs/extras/modules/data_connection/vectorstores/integrations/chroma.ipynb

@@ -146,11 +146,11 @@
     "# save to disk\n",
     "db2 = Chroma.from_documents(docs, embedding_function, persist_directory=\"./chroma_db\")\n",
     "db2.persist()\n",
-    "docs = db.similarity_search(query)\n",
+    "docs = db2.similarity_search(query)\n",
     "\n",
     "# load from disk\n",
-    "db3 = Chroma(persist_directory=\"./chroma_db\")\n",
-    "docs = db.similarity_search(query)\n",
+    "db3 = Chroma(persist_directory=\"./chroma_db\", embedding_function=embedding_function)\n",
+    "docs = db3.similarity_search(query)\n",
     "print(docs[0].page_content)"
    ]
   },