chore(iam): remove guest user support

Author: Gnoale

docs/resources/iam_user.md

@@ -10,16 +10,7 @@ For more information, see the [API documentation](https://www.scaleway.com/en/de
 
 ## Example Usage
 
-### Guest user
-
-```terraform
-resource "scaleway_iam_user" "guest" {
-  email = "[email protected]"
-  tags  = ["test-tag"]
-}
-```
-
-### Member user
+### User
 
 ```terraform
 resource "scaleway_iam_user" "member" {
@@ -31,8 +22,6 @@ resource "scaleway_iam_user" "member" {
 }
 ```
 
-When `username` is set, the user is created as a [Member](https://www.scaleway.com/en/docs/iam/concepts/#member). Otherwise, it is created as a [Guest](https://www.scaleway.com/en/docs/iam/concepts/#guest).
-
 ### Multiple users
 
 ```terraform
@@ -57,7 +46,7 @@ resource "scaleway_iam_user" "user" {
 
 - `tags` - (Optional) The tags associated with the user.
 
-- `username` - (Optional) The username of the IAM user. When it is set, the user is created as a Member. When it is not set, the user is created as a Guest and the username is set as equal to the email.
+- `username` - (Required) The username of the IAM user.
 
 - `password` - The password for first access.
 
@@ -73,8 +62,6 @@ resource "scaleway_iam_user" "user" {
 
 - `locale` - The user's locale (e.g., en_US).
 
-Important: When creating a Guest user, all arguments are ignored, except for `organization_id`, `email` and `tags`.
-
 ## Attributes Reference
 
 In addition to all arguments above, the following attributes are exported: