docs: Added notes on missing SecurityService and is-debug-enabled met…

…hod. [backport docs-release-5.4] (#5012)

docs: Added notes on missing SecurityService and is-debug-enabled method. (#5009)

* Added notes on missing SecurityService and is-debug-enabled method.

* minor rewording

---------

Co-authored-by: nicolatimeus <[email protected]>
(cherry picked from commit c547b91)

Co-authored-by: Salvatore Coppola <[email protected]>

docs/references/rest-apis/rest-security-api.md

@@ -3,6 +3,8 @@
 
     This API can also be accessed via the RequestHandler with app-id: `SEC-V1`.
 
+    This REST API requires a [SecurityService](https://download.eclipse.org/kura/docs/api/5.4.0/apidocs/org/eclipse/kura/security/SecurityService.html) implementation to be registered on the framework, which is not provided by the standard Kura distribution.
+
 
 The `SecurityRestService` APIs provides methods to manage the system security.
 Identities with `rest.security` permissions can access these APIs.
@@ -18,7 +20,7 @@ Identities with `rest.security` permissions can access these APIs.
 ##### Responses
 
 - 200 OK status
-- 500 Internal Server Error
+- 500 Internal Server Error (also returned when no `SecurityService` implementation is available)
 
 #### Reload command line fingerprint
 
@@ -29,11 +31,14 @@ Identities with `rest.security` permissions can access these APIs.
 ##### Responses
 
 - 200 OK status
-- 500 Internal Server Error
+- 500 Internal Server Error (also returned when no `SecurityService` implementation is available)
 
 ## GET methods
 
-#### Debug enabled
+#### Debug enabled 
+!!! note
+
+    Access to this resource doesn't require the `rest.security` permission.
 
 - Description: This method allows you to check whether debug mode is enabled in the system.
 - Method: GET
@@ -47,4 +52,4 @@ Identities with `rest.security` permissions can access these APIs.
     "enabled":true
 }
 ```
-- 500 Internal Server Error
+- 500 Internal Server Error (also returned when no `SecurityService` implementation is available)