DOC-3521: Clarify license keys in AI on-premises credentials table (#4160)

* DOC-3521: Clarify license keys in AI on-premises credentials table

Remove the TINYMCE_API_KEY row and CDN/API key references that do not
apply to on-premises deployments, and distinguish the service license
key from the TinyMCE editor license key.

* DOC-3521: Address review feedback on credentials table

Use consistent "required" wording in the Required column, make the
editor license key requirement specific to premium AI features, and
trim the note so it no longer repeats the introductory paragraph.

* DOC-3521: Clarify when each license key is provided

Note that LICENSE_KEY is passed to the AI service container as an
environment variable, while license_key is added to the editor
configuration, in the credentials table.

Author: kemister85

modules/ROOT/pages/tinymceai-on-premises.adoc

@@ -90,29 +90,24 @@ The shared secret (API Secret) exists only in the application back end (token en
 
 == Credentials
 
-Three credentials are involved in an on-premises deployment. They are distinct and serve different purposes.
+Two license keys are involved in an on-premises deployment. They are distinct, come from different sources, and serve different purposes.
 
 [cols="1,1,2,1",options="header"]
 |===
 |Credential |Where it lives |What it does |Required?
 
-|`LICENSE_KEY`
-|AI service container (environment variable)
-|Activates the AI service. A long string provided by the Tiny account representative.
-|Yes — the service refuses to start without it.
+|Service license key (`LICENSE_KEY`)
+|Passed to the AI service container as an environment variable (for example, in the `docker run` command or Compose file)
+|Activates the on-premises AI service at runtime. A long string provisioned through the {companyname} customer portal.
+|Yes — required to run the service.
 
-|`TINYMCE_API_KEY`
-|Editor page (CDN script URL) or build configuration
-|Authenticates against `cdn.tiny.cloud` when loading {productname} from the CDN. This is the short string from the tiny.cloud dashboard.
-|Only when loading {productname} from the CDN. Omit for self-hosted editor bundles.
-
-|`license_key` (init option)
-|`tinymce.init({ license_key: 'T8LK:...' })`
-|Activates premium {productname} features when using a self-hosted editor bundle (not the CDN).
-|Only for self-hosted editor deployments. Provided by the Tiny account representative.
+|{productname} editor license key (`license_key`)
+|Added to the editor configuration: `tinymce.init({ license_key: 'T8LK:...' })`
+|Configures the license mode for the {productname} editor and activates premium {productname} features.
+|Yes — required for the premium {productname} AI features.
 |===
 
-NOTE: `LICENSE_KEY` (the AI service license) and `TINYMCE_API_KEY` / `license_key` (the editor license) are different credentials from different sources. They are not interchangeable.
+NOTE: The service license key (`LICENSE_KEY`) and the {productname} editor license key (`license_key`) are not interchangeable. For more information, see xref:service-license-keys.adoc[Service license keys] and xref:license-key.adoc[License key].
 
 == Prerequisites