Replace preffix with prefix

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

roles/custom/matrix-prometheus-nginxlog-exporter/templates/prometheus-nginxlog-exporter.yaml.j2

@@ -13,7 +13,7 @@ listen:
 namespaces:
   - name: matrix
     metrics_override:
-      preffix: "myprefix"
+      prefix: "myprefix"
     namespace_label: "namespace"
     format: "$log_source $server_name - $upstream_addr - $remote_addr - $remote_user [$time_local] $host \"$request\" $status \"$http_referer\" \"$http_user_agent\" \"$http_x_forwarded_for\""
     # enable to print to console