Trivial docs edits and rename `@migrate`

[KevinDCarlson]

I thought we'd agreed to name @migrate something different to avoid collision with DataMigrations, so renamed it here, I don't think we want the DataMigrations one to be a method of the Gatlab one. Also a couple of superficial edits to docs. Let me know any thoughts.

[codecov[bot]]

Codecov Report

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

Comparison is base (345cc44) 96.61% compared to head (b885d2d) 96.61%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #126 +/- ## ======================================= Coverage 96.61% 96.61% ======================================= Files 38 38 Lines 2067 2067 ======================================= Hits 1997 1997 Misses 70 70 ```

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[kris-brown]

With https://github.com/AlgebraicJulia/GATlab.jl/pull/118, migrate is now a function, not a macro! Would this make things compatible with DataMigrations?

[KevinDCarlson]

I guess so, right? That's exporting @migrate and migrate, which don't collide. I'm still skeptical about having both of those names present and meaning dramatically different things, in terms of UX. It seems like a pretty common Julian practice to have @f be a sugared version of f.

[KevinDCarlson]

Err, wait...Then I have to think about migrate itself in DataMigrations. That's exported too and we don't want to have those collide either.

[epatters]

My suggestion would still be to have migrate_model and/or @migrate_model. It's only a few more characters but IMO makes it notably more clear what the function/macro does.

[kris-brown]

Great, I updated that PR!