docs: Add ORCID login documentation and email setup steps

[nellh]

Some basic documentation for ORCID accounts on OpenNeuro explaining how accounts work and what is done with the information gathered. Steps included for making an email visible to OpenNeuro.

@effigies This is what I'd like to link to from the warning that no email was readable when a user is logged in with ORCID, what do you think of the wording?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 44.16%. Comparing base (0bf65b0) to head (6e71c04).
Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3180      +/-   ##
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+ Coverage   42.84%   44.16%   +1.31%     
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  Files         549      593      +44     
  Lines       36187    37838    +1651     
  Branches     1132     1132              
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+ Hits        15506    16710    +1204     
- Misses      20479    20926     +447     
  Partials      202      202              

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[effigies]

This is showing a Google login and admin interface. Here's an unprivileged orcid login:

[effigies]

Typo in filename. s/oricd/orcid/

[effigies]

Should add this to the TOC:

openneuro/docs/index.md

Lines 45 to 50 in 0bf65b0

	```{toctree}
	:hidden:
	user_guide
	faq
	```