doc: usage clarification (#2806)

* doc: use scaleway_lb_ip for ip_ids of a scaleway_lb

* doc: specify that a default security group can be created

* fix: correct link

Author: ahamez

docs/resources/instance_server.md

@@ -201,6 +201,8 @@ To retrieve more information by label please use: ```scw marketplace image get l
 
 - `security_group_id` - (Optional) The [security group](https://www.scaleway.com/en/developers/api/instance/#path-security-groups-update-a-security-group9) the server is attached to.
 
+~> **Important:** If you don't specify a security group, a default one will be created, which won't be tracked by Terraform unless you import it.
+
 - `placement_group_id` - (Optional) The [placement group](https://www.scaleway.com/en/developers/api/instance/#path-security-groups-update-a-security-group the server is attached to.
 
 

docs/resources/lb.md

@@ -161,6 +161,8 @@ The following arguments are supported:
 
 - `ip_ids` - (Optional) The List of IP IDs to attach to the Load Balancer.
 
+~> **Important:** Make sure to use a [`scaleway_lb_ip`](./lb_ip.md) resource to create the IPs.
+
 - `ip_id` - (Deprecated) The ID of the associated Load Balancer IP. See below.
 
 ~> **Important:** Updates to `ip_id` will recreate the Load Balancer.