docs: update examples with the sync config example (#3573)

See https://github.com/project-zot/zot/pull/3537

Note this sync timeout is for the entire image. It is not per HTTP request.

Signed-off-by: Andrei Aaron <andreifdaaron@gmail.com>

examples/config-sync.json

@@ -74,7 +74,8 @@
 					"onDemand": true,
 					"tlsVerify": true,
 					"maxRetries": 5,
-					"retryDelay": "30s"
+					"retryDelay": "30s",
+					"syncTimeout": "10m"
 				},
 				{
 					"urls": [