Added missing instructions to change cos process bpmn model

Author: jaboehri

exercises/exercise-6.md

@@ -20,7 +20,7 @@ Solutions to this exercise are found on the branch `solutions/exercise-6`.
       1. An [Intermediate Message Catch Event](../learning/concepts/bpmn/messaging.md#message-intermediate-catching-event) to catch the `goodbyeDic` message from the `dsfdev_hrpProcess`.
       1. An [Intermediate Timer Catch Event](../learning/concepts/bpmn/timer-intermediate-catching-events.md) to end the process if no message is sent by the `dsfdev_hrpProcess` after two minutes.
          Make sure both cases finish with a process [End Event](https://docs.camunda.org/manual/7.17/reference/bpmn20/events/none-events/).
-1. Modify the `dsfdev_cosProcess` to use a [Message End Event](../learning/concepts/bpmn/messaging.md#message-end-event) to trigger the process in file `hrp-process.bpmn`. Figure out the values for the `instantiatesCanonical`, `profile` and `messageName` input parameters of the [Message End Event](../learning/concepts/bpmn/messaging.md#message-end-event) based on the [AcitvityDefinition](../learning/concepts/fhir/activitydefinition.md) in file `hrp-process.xml`.
+1. Modify the `dsfdev_cosProcess` to use a [Message End Event](../learning/concepts/bpmn/messaging.md#message-end-event) to trigger the process in file `hrp-process.bpmn`. Figure out the values for the `instantiatesCanonical`, `profile` and `messageName` input parameters of the [Message End Event](../learning/concepts/bpmn/messaging.md#message-end-event) based on the [AcitvityDefinition](../learning/concepts/fhir/activitydefinition.md) in file `hrp-process.xml`. Change the `Cos Task` element into a Service Task and include the `CosTask` as the implementation.
 1. Modify the process in file `hrp-process.bpmn` and set the _process definition key_ and _version_. Figure out the appropriate values based on the [AcitvityDefinition](../learning/concepts/fhir/activitydefinition.md) in file `hrp-process.xml`.
 1. Add a new process authorization extension element to the ActivityDefinition for `dsfdev_dicProcess` using the [parent organization role coding](../learning/concepts/dsf/examples-for-requester-and-recipient-elements.md) where
      only remote organizations which are part of `medizininformatik-initiative.de` and have the `HRP` role are allowed to request `goodByeDic` messages and only