docs: update installation documentation to include port requirements

- Added a new section detailing the required ports (80, 443, and 3000) for Dokploy installation.
- Included a warning about the necessity of ensuring these ports are free before installation to prevent errors.

Author: Mauricio Siu

apps/docs/content/docs/core/installation.mdx

@@ -51,6 +51,18 @@ import { Callout } from "fumadocs-ui/components/callout";
   Hetzner as the best value-for-money VPS provider.
 </Callout>
 
+### Port Requirements
+
+Before installing Dokploy, ensure the following ports are available on your server:
+
+- **Port 80**: HTTP traffic (used by Traefik)
+- **Port 443**: HTTPS traffic (used by Traefik)
+- **Port 3000**: Dokploy web interface
+
+<Callout type='warn'>
+  **Important:** The installation will fail if any of these ports are already in use. Make sure to stop any services using these ports before running the installation script.
+</Callout>
+
 ### Docker
 
 Dokploy utilizes Docker, so it is essential to have Docker installed on your server. If Docker is not already installed, Dokploy's installation script will install it automatically. Use the following command to install Dokploy:

apps/docs/content/docs/core/manual-installation.mdx

@@ -15,7 +15,7 @@ If you wish to customize the Dokploy installation on your server, you can modify
 
 ## Installation Script
 
-Here is a Bash script for installing Dokploy on a Linux server. Make sure you run this as root on a Linux environment that is not a container, and ensure ports 80 and 443 are free.
+Here is a Bash script for installing Dokploy on a Linux server. Make sure you run this as root on a Linux environment that is not a container, and ensure ports 80, 443, and 3000 are free.
 
 
 ```bash
@@ -50,6 +50,13 @@ install_dokploy() {
         exit 1
     fi
 
+    # check if something is running on port 3000
+    if ss -tulnp | grep ':3000 ' >/dev/null; then
+        echo "Error: something is already running on port 3000" >&2
+        echo "Dokploy requires port 3000 to be available. Please stop any service using this port." >&2
+        exit 1
+    fi
+
     command_exists() {
       command -v "$@" > /dev/null 2>&1
     }