Revise authn reference mentions of JWT

Moving existing content to explain it better.

Author: lmktfy

content/en/docs/reference/access-authn-authz/authentication.md

@@ -270,7 +270,7 @@ kubectl create token jenkins
 eyJhbGciOiJSUzI1NiIsImtp...
 ```
 
-The created token is a signed JSON Web Token (JWT).
+The created token is a signed [JSON Web Token](https://www.rfc-editor.org/rfc/rfc7519) (JWT).
 
 The signed JWT can be used as a bearer token to authenticate as the given service
 account. See [above](#putting-a-bearer-token-in-a-request) for how the token is included
@@ -287,9 +287,11 @@ Secrets can authenticate as the service account. Be cautious when granting permi
 to service accounts and read or write capabilities for Secrets.
 {{< /warning >}}
 
+
+
 ## External integrations
 
-Kubernetes has native support for OpenID Connect (OIDC); see [OpenID Connect tokens](#openid-connect-tokens).
+Kubernetes has native support for JWT and for OpenID Connect (OIDC); see [JSON Web Token authentication](#json-web-token-authentication).
 
 Integrations with other authentication protocols (for example: LDAP, SAML, Kerberos, alternate X.509 schemes)
 can be accomplished using an [authenticating proxy](#authenticating-proxy) or by integrating with an
@@ -304,7 +306,35 @@ If you do issue certificates to clients, it is up to you (as a cloud platform ad
 to make sure that the certificate validity period, and other design choices you make, provide a
 suitable level of security.
 
-### OpenID Connect tokens
+### JSON Web Token authentication
+
+You can configure Kubernetes to authenticate users using [JSON Web Token](https://www.rfc-editor.org/rfc/rfc7519)
+(JWT) compliant tokens. JWT authentication mechanism is used for the ServiceAccount tokens that Kubernetes itself issues,
+and you can also use it to integrate with other identity sources.
+
+The authenticator attempts to parse a raw ID token, verify it's been signed by the configured issuer.
+For externally issued tokens, the public key to verify the signature is discovered from the issuer's public endpoint using OIDC discovery.
+
+The minimum valid JWT payload **must** contain the following claims:
+
+```javascript
+{
+  "iss": "https://example.com",   // must match the issuer.url
+  "aud": ["my-app"],              // at least one of the entries in issuer.audiences must match the "aud" claim in presented JWTs.
+  "exp": 1234567890,              // token expiration as Unix time (the number of seconds elapsed since January 1, 1970 UTC)
+  "<username-claim>": "user"      // this is the username claim configured in the claimMappings.username.claim or claimMappings.username.expression
+}
+```
+
+#### JWT egress selector type
+
+{{< feature-state feature_gate_name="StructuredAuthenticationConfigurationEgressSelector" >}}
+
+The `egressSelectorType` field in the JWT issuer configuration allows you to specify which _egress selector_
+should be used for sending all traffic related to the issuer (discovery, JWKS, distributed claims, etc).
+This feature requires the `StructuredAuthenticationConfigurationEgressSelector` feature gate to be enabled.
+
+#### OpenID Connect tokens
 
 [OpenID Connect](https://openid.net/connect/) is a flavor of OAuth2 supported by
 some OAuth2 providers, notably Microsoft Entra ID, Salesforce, and Google.
@@ -392,21 +422,6 @@ To enable the plugin, configure the following command line arguments for the API
 
 {{< feature-state feature_gate_name="StructuredAuthenticationConfiguration" >}}
 
-JWT Authenticator is an authenticator to authenticate Kubernetes users using JWT compliant tokens.
-The authenticator will attempt to parse a raw ID token, verify it's been signed by the configured issuer.
-The public key to verify the signature is discovered from the issuer's public endpoint using OIDC discovery.
-
-The minimum valid JWT payload must contain the following claims:
-
-```json
-{
-  "iss": "https://example.com",   // must match the issuer.url
-  "aud": ["my-app"],              // at least one of the entries in issuer.audiences must match the "aud" claim in presented JWTs.
-  "exp": 1234567890,              // token expiration as Unix time (the number of seconds elapsed since January 1, 1970 UTC)
-  "<username-claim>": "user"      // this is the username claim configured in the claimMappings.username.claim or claimMappings.username.expression
-}
-```
-
 The configuration file approach allows you to configure multiple JWT authenticators, each with a unique
 `issuer.url` and `issuer.discoveryURL`. The configuration file even allows you to specify [CEL](/docs/reference/using-api/cel/)
 expressions to map claims to user attributes, and to validate claims and user information.
@@ -756,13 +771,7 @@ jwt:
   {{% /tab %}}
   {{< /tabs >}}
 
-##### JWT egress selector type
 
-{{< feature-state feature_gate_name="StructuredAuthenticationConfigurationEgressSelector" >}}
-
-The _egressSelectorType_ field in the JWT issuer configuration allows you to specify which egress selector
-should be used for sending all traffic related to the issuer (discovery, JWKS, distributed claims, etc).
-This feature requires the `StructuredAuthenticationConfigurationEgressSelector` feature gate to be enabled.
 
 ##### Limitations {#oidc-limitations}