docs: clarify requirements for Consul token policies and TTLs (#24167)

As of #24166, Nomad agents will use their own token to deregister services and
checks from Consul. This returns the deregistration path to the pre-Workload
Identity workflow. Expand the documentation to make clear why certain ACL
policies are required for clients.

Additionally, we did not explicitly call out that auth methods should not set an
expiration on Consul tokens. Nomad does not have a facility to refresh these
tokens if they expire. Even if Nomad could, there's no way to re-inject them
into Envoy sidecars for Consul Service Mesh without recreating the task anyways,
which is what happens today. Warn users that they should not set an expiration.

Closes: https://github.com/hashicorp/nomad/issues/20185 (wontfix)
Ref: https://hashicorp.atlassian.net/browse/NET-10262

website/content/docs/configuration/consul.mdx

@@ -116,9 +116,10 @@ agents.
 
 - `token` `(string: "")` - Specifies the token used to provide a per-request ACL
   token. This option overrides the Consul Agent's default token. If the token is
-  not set here or on the Consul agent, it will default to Consul's anonymous policy,
-  which may or may not allow writes. Will default to the `CONSUL_HTTP_TOKEN`
-  environment variable if set.
+  not set here or on the Consul agent, it defaults to Consul's anonymous policy,
+  which may or may not allow writes. Defaults to the `CONSUL_HTTP_TOKEN`
+  environment variable if set. Nomad cannot refresh this token; if the token is
+  deleted, Nomad is not able to communicate with Consul.
 
 - `verify_ssl` `(bool: true)`- Specifies if SSL peer verification should be used
   when communicating to the Consul API client over HTTPS. Will default to the
@@ -334,6 +335,58 @@ consul {
 }
 ```
 
+### Consul ACL policy for Nomad
+
+Nomad agents need access to Consul in order to register themselves in the
+service catalog and discover other Nomad agents via service discovery for
+automatic clustering. Nomad clients use Consul tokens from Workload Identity to
+register services and checks but need permissions on their own token to
+deregister. Nomad servers also create [configuration
+entries][consul_config_entry] for Consul Service Mesh, so the specific
+permissions vary slightly between Nomad servers and clients. The following
+Consul ACL policies represent the minimal permissions Nomad servers and clients
+need.
+
+<Tabs>
+<Tab heading="Nomad Servers">
+
+```hcl
+agent_prefix "" {
+  policy = "read"
+}
+
+node_prefix "" {
+  policy = "write"
+}
+
+service_prefix "" {
+  policy = "write"
+}
+
+acl  = "write"
+mesh = "write"
+```
+
+</Tab>
+<Tab heading="Nomad Clients">
+
+```hcl
+agent_prefix "" {
+  policy = "read"
+}
+
+node_prefix "" {
+  policy = "write"
+}
+
+service_prefix "" {
+  policy = "write"
+}
+```
+
+</Tab>
+</Tabs>
+
 ### Consul Namespace <EnterpriseAlert inline/>
 
 Consul does not allow ACL policies associated with namespaces to use agent
@@ -383,3 +436,4 @@ namespace "nomad-ns" {
 [taskuser]: /nomad/docs/job-specification/task#user "Nomad task Block"
 [consul_bound_aud]: /consul/docs/security/acl/auth-methods/jwt#boundaudiences
 [`consul.namespace`]: /nomad/docs/job-specification/consul#namespace
+[consul_config_entry]: /consul/docs/connect/config-entries

website/content/docs/integrations/consul/acl.mdx

@@ -18,7 +18,9 @@ running in Nomad.
 
 Nomad agents need access to Consul in order to register themselves in the
 service catalog and discover other Nomad agents via service discovery for
-automatic clustering. Nomad servers also create [configuration
+automatic clustering. Nomad clients use Consul tokens from Workload Identity to
+register services and checks but need permissions on their own token to
+deregister. Nomad servers also create [configuration
 entries][consul_config_entry] for Consul Service Mesh, so the specific
 permissions vary slightly between Nomad servers and clients. The following
 Consul ACL policies represent the minimal permissions Nomad servers and clients
@@ -106,6 +108,9 @@ URL][nomad_jwks_url]. Consul servers call this URL to retrieve the public keys
 Nomad uses to sign workload identities. With these keys, Consul is able to
 validate their origin and confirm that they were actually created by Nomad.
 
+Nomad cannot recreate Consul tokens that have been deleted. The auth method
+configuration should never set the `MaxTokenTTL` field.
+
 <CodeBlockConfig highlight="2" filename="auth-method.json">
 
 ```json