Improve documentation for Service Catalog Portfolios configuration

[bgshacklett]

Is your feature request related to a problem? Please describe.
The current documentation for Service Catalog Portfolios is difficult to understand, and doesn't provide enough information to use the feature without referencing other sources.

Describe the feature you'd like
Add useful documentation for the Service Catalog Portfolios feature.

• Provide a real description for each field. Do not just use the name of the field as its definition.
• Ensure that fields which are complex types link to the type.
• Provide further context in the example (what key is used to specify an IPortfolioConfig?)

Additional context
As an example, I would like to see updates similar to the following (technical accuracy not withstanding, as I don't know what the function is, nor what the constraints are, because they are not documented):

export interface IPortfolioConfig {
  /**
   * An human-centered identifier of who manages the portfolio
   * 
   * @remarks
   * Length Constraints: Minimum length of 1. Maximum length of 50.
   */
  readonly provider: t.NonEmptyString;
}

For the main example, it would be helpful to know the full structure of where this object fits. E.g.:

customizations:
  serviceCatalogPortfolios:
    - name:
      ...

[erwaxler]

Hello @bgshacklett , thank you for filing a request with the Landing Zone Accelerator team! I've created a ticket internally for the team to review the Service Catalog documentation.

We will keep this issue open for tracking purposes and keep you aware of any status updates going forward. Thank you for supporting Landing Zone Accelerator!