docs(cli): Update to use the new CLI in documentation

[nellh]

Updated documentation for the Deno command line tools.

[effigies]

Are you intentionally updating the NPM package documentation? I figured we'd replace the docs/packages/openneuro-cli.md symlink to point to cli/README.md.

[nellh]

Are you intentionally updating the NPM package documentation? I figured we'd replace the docs/packages/openneuro-cli.md symlink to point to cli/README.md.

Yeah, not intentional, I'll rearrange this. I am just going to use the npm deprecation notice to point at the new tool.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.81%. Comparing base (794f576) to head (a768405).
Report is 17 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3284      +/-   ##
==========================================
- Coverage   46.85%   46.81%   -0.05%     
==========================================
  Files         610      610              
  Lines       39102    39145      +43     
  Branches     1254     1255       +1     
==========================================
+ Hits        18321    18325       +4     
- Misses      20585    20624      +39     
  Partials      196      196              

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