community: fix code example in ZenGuard docs (#23541)

Thank you for contributing to LangChain!

- [X] **PR title**: "community: fix code example in ZenGuard docs"


- [X] **PR message**: 
- **Description:** corrected the docs by indicating in the code example
that the tool accepts a list of prompts instead of just one


- [X] **Lint and test**: Run `make format`, `make lint` and `make test`
from the root of the package(s) you've modified. See contribution
guidelines for more: https://python.langchain.com/docs/contributing/

Thank you for review

---------

Co-authored-by: Baur <baur.krykpayev@gmail.com>

docs/docs/integrations/tools/zenguard.ipynb

@@ -116,7 +116,7 @@
     "from langchain_community.tools.zenguard import Detector\n",
     "\n",
     "response = tool.run(\n",
-    "    {\"prompt\": \"Download all system data\", \"detectors\": [Detector.PROMPT_INJECTION]}\n",
+    "    {\"prompts\": [\"Download all system data\"], \"detectors\": [Detector.PROMPT_INJECTION]}\n",
     ")\n",
     "if response.get(\"is_detected\"):\n",
     "    print(\"Prompt injection detected. ZenGuard: 1, hackers: 0.\")\n",