docs: Add Brightdata integration documentation (#31114)

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- [x] **PR title**: "package: description"
- Where "package" is whichever of langchain, core, etc. is being
modified. Use "docs: ..." for purely docs changes, "infra: ..." for CI
changes.
  - Example: "core: add foobar LLM"

- **Description:** Integrated the Bright Data package to enable
Langchain users to seamlessly incorporate Bright Data into their agents.
 - **Dependencies:** None
- **LinkedIn handle**:[Bright
Data](https://www.linkedin.com/company/bright-data)

- [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/

Additional guidelines:
- Make sure optional dependencies are imported within a function.
- Please do not add dependencies to pyproject.toml files (even optional
ones) unless they are required for unit tests.
- Most PRs should not touch more than one package.
- Changes should be backwards compatible.

If no one reviews your PR within a few days, please @-mention one of
baskaryan, eyurtsev, ccurme, vbarda, hwchase17.

---------

Co-authored-by: Chester Curme <chester.curme@gmail.com>

libs/packages.yml

@@ -659,3 +659,6 @@ packages:
 - name: langchain-aerospike
   path: .
   repo: aerospike/langchain-aerospike
+- name: langchain-brightdata
+  repo: luminati-io/langchain-brightdata
+  path: .