deprecate nlow nhigh, fix incorrect spec values in docs

[braingram]

This is a follow-up to https://github.com/spacetelescope/jwst/pull/8602 and:

• adds a deprecation comment to the nlow and nhigh parameters
• removes nlow and nhigh from the documentation
• fixes the spec values in the docs

The spec values in the docs do not match the step (see the below linked issue). This PR removes the datatypes and defaults from the "arguments" docs page and adds a link to the spec (which will automatically stay up-to-date with the step).

Link to the updated docs: https://jwst-pipeline--8603.org.readthedocs.build/en/8603/jwst/outlier_detection/arguments.html

Fixes https://github.com/spacetelescope/jwst/issues/8599

Checklist for PR authors (skip items if you don't have permissions or they are not applicable)

• [x] added entry in CHANGES.rst within the relevant release section
• [ ] updated or added relevant tests
• [x] updated relevant documentation
• [x] added relevant milestone
• [x] added relevant label(s)
• [ ] ran regression tests, post a link to the Jenkins job below. How to run regression tests on a PR
• [x] All comments are resolved
• [ ] Make sure the JIRA ticket is resolved properly

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 59.56%. Comparing base (23fb5cd) to head (8ec9813).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #8603 +/- ## ========================================== + Coverage 59.54% 59.56% +0.02% ========================================== Files 391 391 Lines 39292 39285 -7 ========================================== + Hits 23396 23402 +6 + Misses 15896 15883 -13 ```

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