ManifoldCAD docs update

[elalish]

We made a breaking change in #440 to pull the static methods up into module.Manifold, which I think is the right call, but this breaks people's existing scripts in ManifoldCAD.org. I decided to add back in the bare manifold constructors so that those scripts will still run, though I did not add them back into the .d.ts. This means they get a red error telling them to update while their script still runs - this feels like a reasonable compromise for now. Nevermind, I should have tested first. This isn't an option because we get redefinition errors. Now I'm just updating the intro docs.

[geoffder]

Seems like an easy way to quasi-deprecate those functions being at the top-level.

Is the goal to eventually drop these out of the top-level again? If so do you think a notice with a timeline to removal would be necessary, or just give people some time with the annoying red squigglies?

[pca006132]

Interesting, why is there redefinition error? Can you show the error message and the exact location throwing the error? (too lazy to turn on my computer)

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (cbfeed1) 89.67% compared to head (f6698c2) 89.67%.

❗ Current head f6698c2 differs from pull request most recent head 9d04423. Consider uploading reports for the commit 9d04423 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #446   +/-   ##
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  Coverage   89.67%   89.67%           
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  Files          35       35           
  Lines        4243     4243           
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  Hits         3805     3805           
  Misses        438      438           

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[elalish]

It's because we now want to use the pattern e.g. const {cube} = Manifold, but if I've already defined cube = Manifold.cube inside of the worker, then JS won't allow you to redefine cube. I was going to try to add a QuickFix in Monaco to help deal with it, but their documentation is very sparse, so I think it's not worthwhile. I guess we'll just hope Monaco's auto-completion will help guide people to the solution.

[geoffder]

I think people will be able to figure it out. Pretty quick fix to add one line at the top to cover all of the used constructors as well.