[docs] added explanation how to run DPL tasks in k8s

Author: justonedev1

docs/kubernetes_ecs.md

@@ -51,6 +51,14 @@ To deploy a Kubernetes task you can in principle reuse existing control-workflow
 with reusing existing manifests, for example bad quotation of arguments: Mesos runs tasks via shell, which interpreted and stripped quotation from commands. For this reason you can find ready-to-use manifests with all necessary changes
 inside `control-operator/ecs-manifests/control-workflows/*kube-direct*`.
 
+### TaskTemplates
+
+Since some tasks are deployed with known values ahead of time (image, env vars, ...), we added the `TaskTemplate` CR, which stores this data in the cluster so the user doesn't have to define everything every time. You can find all the `TaskTemplate`s in the `ecs-manifests/task-templates` folder. Currently we have templates for DPL, Readout, and StfBuilder/Sender. These templates must be applied to the cluster for the ECS bridge to work.
+
+### DPL and JIT
+
+DPL tasks work similarly to those mentioned before: they use `kubernetes_fairmq` in their workflow YAML manifests. However, there is a problem: JIT tasks' manifests are created the moment they are run. So for now you need to first run the workflow to generate those tasks, then change the control mode after they've been generated. This will be changed in the future.
+
 ## Running tasks (`KubectlTask`)
 
 This method is obsoleted by direct ECS <-> Kubernetes bridge. However it should still work