fix: refactor sqlserver to handle encryption correctly (#31)

## Description

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relates to #1234

## Checklist

- [ ] Issue was linked above
- [ ] Code format was applied: `make fmt`
- [ ] Examples were added / adjusted (see `examples/` directory)
- [x] Docs are up-to-date: `make generate-docs` (will be checked by CI)
- [ ] Unit tests got implemented or updated
- [ ] Acceptance tests got implemented or updated (see e.g. [here](f5f99d1709/stackit/internal/services/dns/dns_acc_test.go))
- [x] Unit tests are passing: `make test` (will be checked by CI)
- [x] No linter issues: `make lint` (will be checked by CI)

Reviewed-on: #31
Reviewed-by: Andre_Harms <andre.harms@stackit.cloud>

docs/resources/postgresflexalpha_instance.md

@@ -55,13 +55,14 @@ import {
 
 - `encryption` (Attributes) The configuration for instance's volume and backup storage encryption.
 
-⚠️ **Note:** This feature is in private preview. Supplying this object is only permitted for enabled accounts. If your account does not have access, the request will be rejected. (see [below for nested schema](#nestedatt--encryption))
+⚠︝ **Note:** This feature is in private preview. Supplying this object is only permitted for enabled accounts. If your account does not have access, the request will be rejected. (see [below for nested schema](#nestedatt--encryption))
 - `instance_id` (String) The ID of the instance.
 - `project_id` (String) The STACKIT project ID.
 - `region` (String) The region which should be addressed
 
 ### Read-Only
 
+- `acl` (List of String) List of IPV4 cidr.
 - `connection_info` (Attributes) The DNS name and port in the instance overview (see [below for nested schema](#nestedatt--connection_info))
 - `id` (String) The ID of the instance.
 - `is_deletable` (Boolean) Whether the instance can be deleted or not.
@@ -77,6 +78,9 @@ Required:
 Optional:
 
 - `access_scope` (String) The access scope of the instance. It defines if the instance is public or airgapped.
+
+Read-Only:
+
 - `instance_address` (String)
 - `router_address` (String)