docs: correct the new demo duration in seconds (#308)

Author: Djaytan

README.md

@@ -16,7 +16,7 @@ Available in [Docker Hub](https://hub.docker.com/r/djaytan/papermc-server).
 
 </div>
 
-## 💻 Demonstration (12 seconds)
+## 💻 Demonstration (20 seconds)
 
 <div align="center">
   <a href="https://asciinema.org/a/725450?autoplay=1" target="_blank"><img src="https://github.com/Djaytan/docker-papermc-server/blob/main/docs/asciinema/demo.gif" alt="asciicast"></a>

docs/user-guide/src/index.md

@@ -2,7 +2,7 @@
 
 A general-purpose, OCI-compliant PaperMC server with streamlined and fine-grained customization options.
 
-## 💻 Demonstration (12 seconds)
+## 💻 Demonstration (20 seconds)
 
 <script src="https://asciinema.org/a/725450.js" id="asciicast-725450" async></script>