docs: fix duplicate step numbering in README Quick Start

Deploy to Kubernetes was numbered 4, same as Containerise Your Adapter;
renumber to 5.

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: tarilabs <matteo.mortari@gmail.com>

Author: tarilabs

README.md

@@ -260,7 +260,7 @@ callbacks.report_results(results)
 print(f"Job completed: {results.id}")
 ```
 
-### 4. Deploy to Kubernetes
+### 5. Deploy to Kubernetes
 
 The eval-hub service will create Kubernetes Jobs for your adapter: