docs: adding s3/gs/azblob access_rules repositories to configuration reference

[tobbbles]

The ability to obtain access_rule files from s3, gs, and azblob was already added and documentation added to the docs/docs/api-access-rules.md page, however it's missing from the configuration reference. This PR adds that documentation to the config schema and updates the configuration reference documentation.

Related issue(s)

#562

Checklist

• I have read the contributing guidelines.
• I am following the
  contributing code guidelines.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security. vulnerability, I
  confirm that I got green light (please contact
  [email protected]) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added or changed the documentation.

Further Comments

[codecov]

Codecov Report

Merging #829 (4c5301f) into master (7504e1e) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #829   +/-   ##
=======================================
  Coverage   62.39%   62.39%           
=======================================
  Files         102      102           
  Lines        4789     4789           
=======================================
  Hits         2988     2988           
  Misses       1528     1528           
  Partials      273      273           

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