doc: Change documentation for new attributes to support OIDC Identity providers

[oarbusi]

Description

Change in docs to add details about new attributes added to federated_settings_identity_provider to support OIDC IdPs

Link to any related issue(s): https://jira.mongodb.org/browse/CLOUDP-220800

Type of change:

• Bug fix (non-breaking change which fixes an issue). Please, add the "bug" label to the PR.
• New feature (non-breaking change which adds functionality). Please, add the "enhancement" label to the PR.
• Breaking change (fix or feature that would cause existing functionality to not work as expected). Please, add the "breaking change" label to the PR.
• This change requires a documentation update
• Documentation fix/enhancement

Required Checklist:

• I have signed the MongoDB CLA
• I have read the contribution guidelines
• I have checked that this change does not generate any credentials and that they are NOT accidentally logged anywhere.
• I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code
• If changes include deprecations or removals, I defined an isolated PR with a relevant title as it will be used in the auto-generated changelog.
• If changes include removal or addition of 3rd party GitHub actions, I updated our internal document. Reach out to the APIx Integration slack channel to get access to the internal document.

Further comments

[lantoli]

maybe it would be good in each attribute to say if it's mandatory depending on the protocol. like... this is mandatory for SAML protocol.

[oarbusi]

Maybe required would not be the right word, since it's not actually required, I'm not sure about it. I'm open to opinions

[pierwill]

Some suggestions. In general, literal values should be in backticks throughout.