Remove dpnp.bitwise_count from a list of miscellaneous mathematical functions

[antonwolfy]

The PR proposes to remove duplicating reference on dpnp.bitwise_count from a list of miscellaneous mathematical functions.
It seems better to have dpnp.bitwise_count listed under bit-wise operations only.

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[github-actions]

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

[coveralls]

coverage: 71.763% (+0.01%) from 71.75%
when pulling b18f6ef on clean-up-rst
into 15b7644 on master.

[github-actions]

Array API standard conformance tests for dpnp=0.18.0dev0=py312he4f9c94_32 ran successfully.
Passed: 1006
Failed: 0
Skipped: 17