Document Okta config in sync guide and related documentation

[adorton-adobe]

We need to document all config attributes in the Okta config file in the User Manual and potentially the User Success Guide.

• brief overview of Okta functionality
• links to relevant Okta API documentation (including procedure for generating API access tokens)
• the following information for each config attribute
  • attribute name
  • brief description
  • accepted values (and/or examples)
  • impact on sync functionality (if applicable)

We shouldn't need to introduce any new command line parameters, but if we do, we need to ensure that any we add are also well-documented,

[adorton-adobe]

Be sure to add that since Okta uses email address to identify users, this module doesn't support username based federated identities.

[adorton-adobe]

We also need to mention that the okta config file does not support user_email_format. Okta always identifies users by email address, and that email is always in the same field.

[adorton-adobe]

@bhunut-adobe - please review.

https://github.com/adorton-adobe/user-sync.py/blob/okta/docs/user-manual/index.md#okta-user-sync

[adorton-adobe]

First version is done