Add glossary page for "registrable domain" instead of "eTLD"

[wbamberg]

I'd like to link to a glossary definition of "registrable domain" in the passkeys guide. It turns out that although we don't have one, we do have a page for eTLD.

But I think "registrable domain" is a better glossary entry, for three reasons:

• "registrable domain" is the spec term. The spec doesn't talk about eTLD AFAICT.
• "registrable domain" is more comprehensible
• we never actually link to "eTLD" we only link to "eTLD+1", which is the same as registrable domain. So we currently have to link into a fragment of the glossary entry, rather than directly to it.

[github-actions]

Preview URLs (15 pages)

• /en-US/docs/Glossary/Registrable_domain
• /en-US/docs/Glossary/Site
• /en-US/docs/Mozilla/Firefox/Releases/92
• /en-US/docs/Web/API/Attribution_Reporting_API/Registering_triggers
• /en-US/docs/Web/API/Attribution_Reporting_API
• /en-US/docs/Web/API/FedCM_API/IDP_integration
• /en-US/docs/Web/API/FedCM_API/RP_sign-in
• /en-US/docs/Web/API/Private_State_Token_API/Using
• /en-US/docs/Web/API/Storage_API/Storage_quotas_and_eviction_criteria
• /en-US/docs/Web/HTTP/Reference/Headers/Attribution-Reporting-Register-Source
• /en-US/docs/Web/Privacy/Guides/Bounce_tracking_mitigations
• /en-US/docs/Web/Privacy/Guides/Privacy_sandbox/Partitioned_cookies
• /en-US/docs/Web/Privacy/Guides/Redirect_tracking_protection
• /en-US/docs/Web/Privacy/Guides/State_Partitioning
• /en-US/docs/Web/Privacy/Guides/Storage_Access_Policy

Flaws (6)

Note! 12 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Web/API/Attribution_Reporting_API
Title: Attribution Reporting API
Flaw count: 1

• unknown:
  • Error parsing /shared-assets/images/diagrams/api/attribution-reporting/ara-flow.svg: No such file or directory (os error 2)

---

URL: /en-US/docs/Web/API/Private_State_Token_API/Using
Title: Using the Private State Token API
Flaw count: 2

• macros:
  • Macro domxref produces link /en-US/docs/Web/API/fetch which is a redirect
  • Macro domxref produces link /en-US/docs/Web/API/fetch which is a redirect

---

URL: /en-US/docs/Web/HTTP/Reference/Headers/Attribution-Reporting-Register-Source
Title: Attribution-Reporting-Register-Source header
Flaw count: 3

• unknown:
  • No generic content config found
  • no blog root
  • no blog root

External URLs (5)

URL: /en-US/docs/Glossary/Registrable_domain
Title: Registrable domain

• https://publicsuffix.org/ (2 times) (Note! This may be a new URL 👀)
• https://url.spec.whatwg.org/ (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Firefox/Releases/92
Title: Firefox 92 release notes for developers

• https://bugzil.la/1064466 (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/Private_State_Token_API/Using
Title: Using the Private State Token API

• https://github.com/GoogleChromeLabs/private-state-token-demo/ (1 time) (Note! This may be a new URL 👀)
• https://github.com/GoogleChromeLabs/private-state-token-demo/blob/bf173919620f2b8203a628c3a1094c8846e6aff1/src/index.js (3 times) (Note! This may be a new URL 👀)