docs: document variadic parameters with leading star

[antonwolfy]

Summary

Several docstrings documented variadic parameters without the leading */**, so the rendered type read like a single value rather than a sequence of arguments. This aligns them with the numpydoc convention (and with dpnp.broadcast / dpnp.broadcast_arrays / dpnp.broadcast_shapes, which already use *args).

Changes (documentation only, no behavior change):

• apply_along_axis: args / kwargs -> *args / **kwargs
• check_supported_arrays_type: arrays -> *arrays
• _compute_res_dtype: arrays -> *arrays

Checklist

• Have you provided a meaningful PR description?
• Have you added a test, reproducer or referred to an issue with a reproducer?
• Have you tested your changes locally for CPU and GPU devices?
• Have you made sure that new changes do not introduce compiler warnings?
• Have you checked performance impact of proposed changes?
• Have you added documentation for your changes, if necessary?
• Have you added your changes to the changelog?

[github-actions]

View rendered docs @ https://intelpython.github.io/dpnp/pull/3032/index.html

[github-actions]

Array API standard conformance tests for dpnp=0.21.0dev5=py314ha0e2e8e_4 ran successfully.
Passed: 1376
Failed: 1
Skipped: 5

[coveralls]

coverage: 78.461% (+0.003%) from 78.458% — docs/variadic-args-star into master