feat(dev): Add IInternalTaskType docs

Signed-off-by: Marcel Klehr <mklehr@gmx.net>

Author: marcelklehr

developer_manual/digging_deeper/task_processing.rst

@@ -14,7 +14,7 @@ Consuming the Task Processing API
 To consume the  Task Processing API, you will need to :ref:`inject<dependency-injection>` ``\OCP\TaskProcessing\IManager``. This manager offers the following methods:
 
  * ``hasProviders()`` This method returns a boolean which indicates if any providers have been registered. If this is false you cannot use the TextProcessing feature.
- * ``getAvailableTaskTypes(bool $showDisabled = false)`` This method returns an array of enabled task types indexed by their ID with their names and additional metadata. If you set ``$showdisabled`` to ``true`` (available since NC31), it will include disabled task types.
+ * ``getAvailableTaskTypes(bool $showDisabled = false)`` This method returns an array of enabled task types indexed by their ID with their names and additional metadata. If you set ``$showdisabled`` to ``true`` (available since NC31), it will include disabled task types. Since NC33 this will also include the `isInternal` field that signifies whether the task type is user-facing or intended for internal use only.
  * ``getAvailableTaskTypeIds()`` This method (available since NC32) returns a list of available task type IDs. It uses the same logic as ``getAvailableTaskTypes()`` but is faster because it does not compute the task types metadata (which can be slow when getting default field values or multiselect value lists). If you just want to check if a feature is available, prefer using this method rather than ``getAvailableTaskTypes()``.
  * ``scheduleTask(Task $task)`` This method provides the actual scheduling functionality. The task is defined using the Task class. This method runs the task asynchronously in a background job.
  * ``getTask(int $id)`` This method fetches a task specified by its id.
@@ -530,6 +530,16 @@ If you would like to implement providers that handle additional task types, you
     	}
     }
 
+Internal task types
+~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 33.0.0
+
+Other apps and clients will assume that task types are user-facing and will display them on the frontend. If your custom
+task types are not intended to be shown to users, you should implement the `IInternalTaskType` interface instead. This will
+make sure that other apps and clients know not to show your custom task type to end users.
+
+
 Provider and task type registration
 -----------------------------------