Improve update request feedback and documentation

[vigoo]

When a worker update is initiated through the CLI or the REST API, it is not happening immediately, just get enqueued.

This should be made more clear by:

• mentioning this in the documentation (learn.golem.cloud)
• changing the Updated response in CLI to something more descriptive (at least "Update request sent")
• the REST API should response with 202 not 200

[justcoon]

in relation to cli, golem-cli worker get ... --format text it look like that text output do not showing updates https://github.com/golemcloud/golem/blob/main/golem-cli/src/model/text.rs#L747-L784 it would be nice to see there at least last update, especially if it is error

[vigoo]

There is proper feedback now in the CLI output about updates, and it is even possible to await until it's done.