[add] added maximum client and demo client protection

- default demo clients can no longer be modified/deleted when in demo mode
 - increased default demo reset to 60 minutes

api.yml

@@ -1,11 +1,34 @@
 openapi: "3.0.0"
 info:
-  description: "Simple dynDNS via Rest-API."
+  description: "Simple dynDNS via Rest-API.
+
+
+  The demo database will reset every **60** minutes. A maximum of 250 clients can exist in the demo database.
+
+  The following default clients and api keys can be used:
+
+| client name  | api key                                                                                  |
+
+|--------------|------------------------------------------------------------------------------------------|
+
+| admin        | `zW3If4s5.41a7c846.23b142e6451df545d5034ca8f6050b80ff3e9689f20d5e45d72d160fa7e1cf32` |
+
+| read_client  | `zW3If4s5.28aef5cb.d502cb94ba0802c6363f95ecb3a70de7e2e4b889779e435b7c033f2c72ed4f20` |
+
+| write_client | `zW3If4s5.3d6129cc.48d41d2a28b16a9a274d3f407026aee2b82cddbb3c11a5496ffe329c78e5d54b` |
+
+  In `demo-mode` it is not possible to call `POST /admin/client`, `PUT /admin/client` or `DELETE /admin/clients/{client_name}` for any of the above default clients. Any newly created client can be freely modified.
+
+
+  ***Note**: the X-API-Key value entered when using Authorize takes precedence over values entered in the X-API-Key parameters field.
+
+  Since the X-API-Key parameter field is flagged as required a simple space (or any other character) will still be needed for executing the request here.*
+  "
   version: "1.0"
   title: "rynDNS"
 
 servers:
-  - url: "https://api.pdev.dev/rynDNS/v1"
+  - url: "https://demo.api.pdev.dev/rynDNS"
     description: ""
 
 security:
@@ -49,6 +72,8 @@ paths:
           description: "Invalid input"
         "406":
           description: "Not Acceptable - Can not remove last admin account permissions"
+        "429":
+          description: "Too many clients - Maximum client count reached"
     put:
       tags:
         - "admin"
@@ -356,5 +381,5 @@ components:
       example: "115.16.0.99"
       pattern: "^(((25[0-5]|(2[0-4]|1[0-9]|[1-9]|)[0-9])(.(?!$)|$)){4})?$"
 externalDocs:
-  description: "Source"
-  url: "https://git.pdev.dev"
+  description: "<rynDNS source code>"
+  url: "https://git.pdev.dev/pdev/ryndns"