message: Update docs to match reality.
diff: @@ -203,13 +203,10 @@ export class GoogleAnalytics implements AnalyticsApi {
  * - With value `User:default/name`, userId becomes `sha256(User:default/name)`
  *
  * If an integrator wishes to use an alternative hashing mechanism or an
  - * entirely different value, they may do so by passing a dummy Identity API
  - * implementation which returns a `userEntityRef` whose kind is the literal
  - * string `PrivateUser`, whose namespace is anything (it will be ignored) and
  - * whose name is the pre-hashed ID value.
  - *
  - * - With value `PrivateUser:default/a0n3b4n3`, userId becomes `a0n3b4n3`
  - * - With `PrivateUser:xyz/a0n3b4n3`, userId is `a0n3b4n3`
  + * entirely different value, they may do so by passing a `userIdTransform`
  + * function alongside the `identityApi` to `GoogleAnalytics.fromConfig()`.
  + * This function receives the `userEntityRef` as an argument and should
  + * resolve to a hashed version of whatever identifier they choose.
  *
  * Note: this feature requires that an integrator has set up a Google
  * Analytics User ID view in the property used to track Backstage.
  @@ -228,7 +225,8 @@ export class GoogleAnalytics implements AnalyticsApi {
  }
  /**
  - * Returns a PII-free user ID for use in Google Analytics.
  + * Returns a PII-free (according to Google's terms of service) user ID for
  + * use in Google Analytics.
  */
  private getPrivateUserId(userEntityRef: string): Promise<string> {
  // Allow integrators to provide their own hashing transformer.
  