[no-ci] Update contributor guide to encourage communication prior to work (#2173)

* docs: add issue claiming guidance to contributor docs

* docs: fix bullet point formatting in cuda_bindings contribute.rst

* docs: revert issue claiming guidance from cuda_bindings contribute.rst

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: leofang

CONTRIBUTING.md

@@ -9,7 +9,8 @@ Thank you for your interest in contributing to CUDA Python! Based on the type of
     them for a release. If you believe the issue needs priority attention
     comment on the issue to notify the team.
 2. You want to implement a feature, improvement, or bug fix:
-    - Please refer to each component's guideline:
+   - Before starting work on an existing issue, please comment on the issue to express your interest and wait to be assigned by a maintainer. This helps avoid redundant effort in case the issue is already being worked on by another contributor or an NVIDIA team member.
+   - Please refer to each component's guideline:
        - [`cuda.core`](https://nvidia.github.io/cuda-python/cuda-core/latest/contribute.html)
        - [`cuda.bindings`](https://nvidia.github.io/cuda-python/cuda-bindings/latest/contribute.html)<sup>[1](#footnote1)</sup>
        - [`cuda.pathfinder`](https://nvidia.github.io/cuda-python/cuda-pathfinder/latest/contribute.html)

cuda_core/docs/source/contribute.rst

@@ -18,4 +18,5 @@ Thank you for your interest in contributing to ``cuda-core``! Based on the type
 
 2. You want to implement a feature, improvement, or bug fix:
 
+   - Before starting work on an existing issue, please comment on the issue to express your interest and wait to be assigned by a maintainer. This helps avoid redundant effort in case the issue is already being worked on by another contributor or an NVIDIA team member.
    - Please ensure that your commits are signed `following GitHub's instruction <https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification>`_.

cuda_pathfinder/docs/source/contribute.rst

@@ -14,4 +14,5 @@ Thank you for your interest in contributing to ``cuda-pathfinder``! Based on the
       them for a release. If you believe the issue needs priority attention
       comment on the issue to notify the team.
 2. You want to implement a feature, improvement, or bug fix
+    - Before starting work on an existing issue, please comment on the issue to express your interest and wait to be assigned by a maintainer. This helps avoid redundant effort in case the issue is already being worked on by another contributor or an NVIDIA team member.
     - Please ensure that your commits are signed `following GitHub's instruction <https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification>`_.