add swap setup instructions to README prerequisites

README.md

@@ -46,7 +46,7 @@ graph TB
 
 ## Prerequisites
 
-- A VPS with SSH access
+- A VPS with SSH access (minimum 1 core, 3 GB RAM)
 - Domain `t-gstone.de` with DNS control
 - Git installed locally
 
@@ -56,6 +56,18 @@ Check your VPS OS:
 cat /etc/os-release
 ```
 
+### Swap (recommended)
+
+If your VPS has no swap, add a 2 GB swapfile to prevent OOM kills:
+
+```bash
+sudo fallocate -l 2G /swapfile
+sudo chmod 600 /swapfile
+sudo mkswap /swapfile
+sudo swapon /swapfile
+echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
+```
+
 ## DNS Setup
 
 Create these A records pointing to your VPS IP: