docs: add Terraform/OpenTofu provider page (#2967)

Author: Josh-Archer

docs/extending-seerr/terraform-provider.mdx

@@ -0,0 +1,62 @@
+---
+title: Terraform/OpenTofu Provider (Advanced)
+description: Manage Seerr settings and integrations with the community Terraform/OpenTofu provider.
+sidebar_position: 4
+---
+
+# Terraform/OpenTofu Provider (Advanced)
+
+:::warning
+This provider is maintained by the community, not by the Seerr team. Please report bugs or feature requests in the [provider repository](https://github.com/Josh-Archer/terraform-provider-seerr).
+:::
+
+The community-maintained [Seerr Terraform/OpenTofu provider](https://search.opentofu.org/provider/josh-archer/seerr/latest) can manage Seerr settings and integrations from infrastructure-as-code workflows.
+
+## Basic Example
+
+Configure the provider with your Seerr URL and API key, then manage Seerr resources in the same configuration as the rest of your infrastructure.
+
+```hcl
+terraform {
+  required_providers {
+    seerr = {
+      source = "registry.opentofu.org/josh-archer/seerr"
+    }
+  }
+}
+
+variable "seerr_api_key" {
+  type      = string
+  sensitive = true
+}
+
+provider "seerr" {
+  url                  = "https://seerr.example.com"
+  api_key              = var.seerr_api_key
+  insecure_skip_verify = false # Set to true for self-signed certificates.
+}
+
+resource "seerr_main_settings" "main" {
+  app_title               = "Seerr"
+  application_url         = "https://seerr.example.com"
+  locale                  = "en"
+  movie_requests_enabled  = true
+  series_requests_enabled = true
+}
+```
+
+The provider also includes resources and data sources for common Seerr integrations:
+
+- Plex
+- Jellyfin
+- Emby
+- Radarr
+- Sonarr
+- Tautulli
+- Notifications
+- Users
+- Permissions
+- Requests
+- Issues
+- Background job schedules
+- And many more.