[Doc] Clarify the relation between 'uv run' and 'uv pip' support (ray-project#51599)

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## Why are these changes needed?

Fixes ray-project#51195

## Related issue number

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Signed-off-by: Dhakshin Suriakannu <d_suriakannu@apple.com>

Author: pcmoritz

doc/source/ray-core/handling-dependencies.rst

@@ -526,7 +526,11 @@ The ``runtime_env`` is a Python dictionary or a Python class :class:`ray.runtime
   When specifying a path to a ``requirements.txt`` file, the file must be present on your local machine and it must be a valid absolute path or relative filepath relative to your local current working directory, *not* relative to the ``working_dir`` specified in the ``runtime_env``.
   Furthermore, referencing local files *within* a ``requirements.txt`` file isn't directly supported (e.g., ``-r ./my-laptop/more-requirements.txt``, ``./my-pkg.whl``). Instead, use the ``${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}`` environment variable in the creation process. For example, use ``-r ${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}/my-laptop/more-requirements.txt`` or ``${RAY_RUNTIME_ENV_CREATE_WORKING_DIR}/my-pkg.whl`` to reference local files, while ensuring they're in the ``working_dir``.
 
-- ``uv`` (dict | List[str] | str): Alpha version feature. Either (1) a list of uv `requirements specifiers <https://pip.pypa.io/en/stable/cli/pip_install/#requirement-specifiers>`_, (2) a string containing
+- ``uv`` (dict | List[str] | str): Alpha version feature. This plugin is the ``uv pip`` version of the ``pip`` plugin above. If you
+  are looking for ``uv run`` support with ``pyproject.toml`` and ``uv.lock`` support, use
+  :ref:`the uv run runtime environment plugin <use-uv-for-package-management>` instead.
+
+  Either (1) a list of uv `requirements specifiers <https://pip.pypa.io/en/stable/cli/pip_install/#requirement-specifiers>`_, (2) a string containing
   the path to a local uv `“requirements.txt” <https://pip.pypa.io/en/stable/user_guide/#requirements-files>`_ file, or (3) a python dictionary that has three fields: (a) ``packages`` (required, List[str]): a list of uv packages,
   (b) ``uv_version`` (optional, str): the version of uv; Ray will spell the package name "uv" in front of the ``uv_version`` to form the final requirement string.
   (c) ``uv_check`` (optional, bool): whether to enable pip check at the end of uv install, default to False.