docs: Add instance-directory comment

Author: Alan Christie

workflow/workflow_abc.py

@@ -240,6 +240,12 @@ def get_running_workflow_step(
         # }
         # If not present an empty dictionary should be returned.
         #
+        # Additionally, if the step has started (an instance has been created)
+        # the response will contain a "instance_directory" top-level property
+        # that is the directory within the Project that's the step's working directory.
+        #
+        #       "instance_directory": ".instance-00000000-0000-0000-0000-00000000000a",
+        #
         # For steps that are not the first in a workflow the following field
         # can be expected in the response: -
         #
@@ -273,6 +279,12 @@ def get_running_workflow_step_by_name(
         # }
         # If not present an empty dictionary should be returned.
         #
+        # Additionally, if the step has started (an instance has been created)
+        # the response will contain a "instance_directory" top-level property
+        # that is the directory within the Project that's the step's working directory.
+        #
+        #       "instance_directory": ".instance-00000000-0000-0000-0000-00000000000a",
+        #
         # For steps that are not the first in a workflow the following field
         # can be expected in the response: -
         #
@@ -322,6 +334,12 @@ def get_workflow_steps_driving_this_step(
         #       }
         #     ]
         # }
+        #
+        # Additionally, if the step has started (an instance has been created)
+        # each entry on the array of steps will contain a "instance_directory" property
+        # that is the directory within the Project that's the step's working directory.
+        #
+        #       "instance_directory": ".instance-00000000-0000-0000-0000-00000000000a",
 
     @abstractmethod
     def get_instance(self, *, instance_id: str) -> tuple[dict[str, Any], int]: