Fix organization ruleset conditions schema validation, update docs

[o-sama]

Resolves #1899 & #1909

---

Before the change?

• Validation on organization_ruleset.conditions.0 was partially broken.
  • It correctly prevented setting both repository_name and repository_id.
  • It incorrectly allowed setting neither repository_name nor repository_id.
• Documentation for bypass_actors didn't specify anything related to actor_id when setting type to OrganizationAdmin, the API docs also don't mention anything but the expected value is 1 as tested by @YElyousfi.

After the change?

• At least one of repository_name and repository_id is required for organization rulesets conditions, previously this would fail on apply since the API requires at least one to be set alongside ref_name. This shouldn't require a major version change because requests sent using the previous iteration weren't actually succeeding, so there shouldn't be a state change or breakage of existing use.
• Updated docs for both of the issues mentioned in the before section.

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes
• No

---

[lewismiddleton]

I left a comment on #1899 with some more bypass actor_id quirkiness. Could expand the scope of this PR to address that too.

I've also opened #1915 which may be of interest to you.

[nickfloyd]

Thanks for the commits here! ❤️