Improve superdataset commit message

[jwodder]

Closes #353.

[codecov[bot]]

Codecov Report

Patch coverage: 61.33% and project coverage change: -0.35 :warning:

Comparison is base (8cd2700) 76.24% compared to head (0eb733a) 75.90%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## draft #354 +/- ## ========================================== - Coverage 76.24% 75.90% -0.35% ========================================== Files 14 14 Lines 2488 2548 +60 Branches 550 568 +18 ========================================== + Hits 1897 1934 +37 - Misses 438 451 +13 - Partials 153 163 +10 ``` | [Impacted Files](https://app.codecov.io/gh/dandi/dandisets/pull/354?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi) | Coverage Δ | | |---|---|---| | [tools/backups2datalad/adataset.py](https://app.codecov.io/gh/dandi/dandisets/pull/354?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi#diff-dG9vbHMvYmFja3VwczJkYXRhbGFkL2FkYXRhc2V0LnB5) | `78.59% <27.77%> (-1.13%)` | :arrow_down: | | [tools/backups2datalad/datasetter.py](https://app.codecov.io/gh/dandi/dandisets/pull/354?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi#diff-dG9vbHMvYmFja3VwczJkYXRhbGFkL2RhdGFzZXR0ZXIucHk=) | `74.63% <68.00%> (-1.20%)` | :arrow_down: | | [tools/backups2datalad/aioutil.py](https://app.codecov.io/gh/dandi/dandisets/pull/354?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi#diff-dG9vbHMvYmFja3VwczJkYXRhbGFkL2Fpb3V0aWwucHk=) | `73.23% <100.00%> (+0.38%)` | :arrow_up: | | [tools/backups2datalad/util.py](https://app.codecov.io/gh/dandi/dandisets/pull/354?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi#diff-dG9vbHMvYmFja3VwczJkYXRhbGFkL3V0aWwucHk=) | `77.14% <100.00%> (ø)` | | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/dandi/dandisets/pull/354/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi)

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[yarikoptic]

Great - thank you! Let's see in action!