Document module configuration options in WPNuxtConfig

[vernaillen]

e.g.:

export interface WPNuxtConfig {
  /**
   * Log level for the WPNuxt module
   * @default 3
   */
  logLevel?: LogLevel

  /**
   * URL of the WordPress site
   *
   * There is no default value for this option, so it's required.
   *
   * @example 'https://wordpress.wpnuxt.com'
   */
  wordpressUrl: string

  /**
   * Download the GraphQL schema and store it on disk.
   *
   * When setting this to false, the module will expect a graphql.schema file to be available.
   * You could first enable this, commit the schema file and then set downloadSchema to false to avoid have to query the graphql introspection on each start of the application
   *
   * @default true
   */
  downloadSchema?: boolean
}