docs: fix typo (#29012)

Thank you for contributing to LangChain!

- [x] **PR title**: "docs: fix typo"

- [x] **PR message**: ***Delete this entire checklist*** and replace
with
    - **Description:** a minor fix of typo
    - **Issue:** NA
    - **Dependencies:** NA
    - **Twitter handle:** NA


- [x] **Add tests and docs**: If you're adding a new integration, please
include
1. ~~a test for the integration, preferably unit tests that do not rely
on network access,~~
2. ~~an example notebook showing its use. It lives in
`docs/docs/integrations` directory.~~


- [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/

libs/packages.yml

@@ -1,4 +1,4 @@
-# this file is used to definet he packages that are used in the project
+# this file is used to define the packages that are used in the project
 # it is EXPERIMENTAL and may be removed in the future
 
 packages: