Task Management Documentation - update example on taskID:1 and task_id:1(in update-by-query)

[matt-isett]

Elasticsearch version:
5.X - 6.X

Description:
Document update needed change from taskid:1 to Nodeid:1 or just taskID which is Nodeid:taskid.

While reading update-by-query; the docs reference taskid as how to get the task information

GET /_tasks/taskId:1

but does not call out what taskId is. It is not the taskID but the Node ID followed by a colon.

When you follow the link over to the main task management docs; it also references a task id but in a different format and seems to say the task id, but again it is the node id.

GET _tasks/task_id:1 

[elasticmachine]

Pinging @elastic/es-distributed

[bleskes]

@nik9000 @imotov I know this was a conscious choice from previous discussions. Care to comment?

[imotov]

I think it should be just taskId as it was in the original version, because the entire thing is essentially a taskId. In other words, it should be: GET /_tasks/taskId. At the moment, the taskId is indeed represented as nodeId:Number, but this might change in the future releases, and we don't want to make it a documented "feature" that users rely on, only to break it in the future releases.

However, I would like to hear @nik9000's opinion since it looks like he changed it from taskId to taskId:1 two years ago, and I am not sure I fully understand reasons behind this change.

[nik9000]

I think it should be just taskId as it was in the original version, because the entire thing is essentially a taskId.

+1. I changed it in the past so it'd parse when I converted the example to // CONSOLE so we'd execute it. We have better tools now, so I can revert it so it makes sense again.