providers/heroku: add heroku_app_feature resource (hashicorp#14035)

r/app_feature.html.markdown

@@ -0,0 +1,28 @@
+---
+layout: "heroku"
+page_title: "Heroku: heroku_app_feature"
+sidebar_current: "docs-heroku-resource-app-feature"
+description: |-
+  Provides a Heroku App Feature resource. This can be used to create and manage App Features on Heroku.
+---
+
+# heroku\_app\_feature
+
+Provides a Heroku App Feature resource. This can be used to create and manage App Features on Heroku.
+
+## Example Usage
+
+```hcl
+resource "heroku_app_feature" "log_runtime_metrics" {
+  app = "test-app"
+  name = "log-runtime-metrics"
+}
+```
+
+## Argument Reference
+
+The following arguments are supported:
+
+* `app` - (Required) The Heroku app to link to.
+* `name` - (Required) The name of the App Feature to manage.
+* `enabled` - (Optional) Whether to enable or disable the App Feature. The default value is true.