Docs: Add secondsToLive to the SA HTTP API docs (#96518)

* Docs: Add secondsToLive param to the SA HTTP API docs

* Docs: Add secondsToLive param to the SA HTTP API docs

docs/sources/developers/http_api/serviceaccount.md

@@ -445,10 +445,13 @@ Content-Type: application/json
 Authorization: Basic YWRtaW46YWRtaW4=
 
 {
-	"name": "grafana"
+	"name": "grafana",
+	"secondsToLive": 604800
 }
 ```
 
+Default value for the `secondsToLive` is 0, which means that the service account token will never expire.
+
 **Example Response**:
 
 ```http