Merge branch 'docs/pages-unique-domain-url' into 'master'

Docs: Update Pages unique domain url browser cache

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/166889



Merged-by: Amy Qualls <aqualls@gitlab.com>
Approved-by: Amy Qualls <aqualls@gitlab.com>
Reviewed-by: Amy Qualls <aqualls@gitlab.com>
Co-authored-by: Naman Jagdish Gala <ngala@gitlab.com>

doc/user/project/pages/getting_started_part_one.md

@@ -39,8 +39,9 @@ Pages domains are `*.gitlab.io`.
 | Project pages owned by a group | `acmecorp/webshop` | `http(s)://acmecorp.example.io/webshop`|
 | Project pages owned by a subgroup | `acmecorp/documentation/product-manual` | `http(s)://acmecorp.example.io/documentation/product-manual`|
 
-When **Use unique domain** setting is enabled, all URLs
-are flattened with the following structure:
+When the **Use unique domain** setting is enabled, Pages builds a unique domain name from
+the flattened project name and a six-character unique ID. Users receive a `308 Permanent Redirect` status 
+redirecting the browser to these unique domain URLs. Browsers might cache this redirect:
 
 | Type of GitLab Pages              | Example path of a project in GitLab     | Website URL |
 | --------------------------------- | --------------------------------------- | ----------- |