Update install to install from release tarball instead of a git repo

[koenpunt]

Now that we switched to using releases, instead of a simple clone/pull of the master branch, we should think of switching to simply downloading a release tarbal

curl https://github.com/creationix/nvm/archive/v0.10.0.tar.gz | \
  tar -xzC ~/.nvm --strip-components=1

[ljharb]

The issues I see are:

• That would download more information than a git delta
• that would hamper development, due to Tests don't all pass consistently #379 and similar

[koenpunt]

I don't see the relation with #379.. Or do you mean that you won't be testing nvm from the .nvm dir?

[ljharb]

Right - if we don't install from git, then the NVM_DIR won't be a git repo, so it won't have any tests in it to run.

[ljharb]

@WGawyjyc please don't post spam, or LLM-generated slop, or off-topic stuff.