Mention removed top_hash parameter in `push()` docs

[codecov[bot]]

Codecov Report

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

Project coverage is 38.42%. Comparing base (536d703) to head (0603c6f). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #4116 +/- ## ======================================= Coverage 38.42% 38.42% ======================================= Files 724 724 Lines 33274 33274 Branches 4899 4899 ======================================= Hits 12785 12785 Misses 19340 19340 Partials 1149 1149 ``` | [Flag](https://app.codecov.io/gh/quiltdata/quilt/pull/4116/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=quiltdata) | Coverage Δ | | |---|---|---| | [api-python](https://app.codecov.io/gh/quiltdata/quilt/pull/4116/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=quiltdata) | `90.85% <ø> (ø)` | | | [catalog](https://app.codecov.io/gh/quiltdata/quilt/pull/4116/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=quiltdata) | `11.43% <ø> (ø)` | | | [lambda](https://app.codecov.io/gh/quiltdata/quilt/pull/4116/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=quiltdata) | `87.95% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=quiltdata#carryforward-flags-in-the-pull-request-comment) to find out more.

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