Add canceled status to Task statuses in all SDK's README

[alallema]

Description
Currently, the different statuses are listed in the readme after an example.
In v0.30 the canceled status was added to the API return Task statuses but was not updated in the readme:

With the uid, you can check the status (enqueued, processing, succeeded or failed) of your documents addition using the task.

It should be updated.

[brunoocasali]

Raising a question:
Is it valid to duplicate the role of the documentation in this kind of code? If we only keep the link, we don't need to worry about it again...

In any case I agree with the change @alallema.

[bidoubiwa]

Maybe we could change this:

Tasks such as document addition always return a unique identifier. You can use this identifier taskUid to check the status (enqueued, processing, succeeded or failed) of a task.

To this:

Tasks such as document addition always return a unique identifier. You can use this identifier `taskUid` to check the status of a [task](https://docs.meilisearch.com/reference/api/tasks.html#get-task).

So that we avoid having to maintain that sort of documentation in the readme's.

What do you think?

[alallema]

So that we avoid having to maintain that sort of documentation in the readme's.

Yes I agree it's also good not to put all the possible status, but maybe we should add something like

Tasks such as document addition always return a unique identifier. You can use this identifier `taskUid` to check the status of a [task](https://docs.meilisearch.com/reference/api/tasks.html#get-task) and see if it has been processed.

To be sure the user know that the task is asynchrone.

[bidoubiwa]

I like that!

[brunoocasali]

Done!