docs: added a link to the taxonomy of labels in the contributing guide for easy access (#28719)

Thank you for contributing to LangChain!

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


- [ ] **PR message**: ***Delete this entire checklist*** and replace
with
- **Description:** Added a link to make it easier to organize github
issues for langchain.
- **Issue:** After reading that there was a taxonomy of labels I had to
figure out how to find it.
    - **Dependencies:** None
    - **Twitter handle:** None


- [ ] **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.


- [ ] **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 you are adding something to community, do not re-import it in
langchain.

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

---------

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

docs/docs/contributing/index.mdx

@@ -37,7 +37,11 @@ If you are able to help answer questions, please do so! This will allow the main
 
 Our [issues](https://github.com/langchain-ai/langchain/issues) page is kept up to date with bugs, improvements, and feature requests.
 
-There is a taxonomy of labels to help with sorting and discovery of issues of interest. Please use these to help organize issues.
+There is a [taxonomy of labels](https://github.com/langchain-ai/langchain/labels?sort=count-desc)
+to help with sorting and discovery of issues of interest. Please use these to help
+organize issues. Check out the [Help Wanted](https://github.com/langchain-ai/langchain/labels/help%20wanted)
+and [Good First Issue](https://github.com/langchain-ai/langchain/labels/good%20first%20issue)
+tags for recommendations.
 
 If you start working on an issue, please assign it to yourself.