GitLab

* remove num_workers.

* remove num_workers.

* remove num_workers.

* remove num-servers.

* update error message.

* update docstring.

* fix docs.

* fix tests.

* fix test.

* fix.

* print messages in test.

* fix.

* fix test.

* fix.
Co-authored-by: Ubuntu <ubuntu@ip-172-31-9-132.us-west-1.compute.internal>

* reorg

* change titles

* rm some stale API doc; minor fix

* fix docs

* add warning

* rm new-tutorial run in ci

* lint

* [Doc] Add Chapter 7

* [Doc] Add CN part 7, 7.1, 7.2, and 7.3

* [Doc] Add CN part 7, 7.1, 7.2, and 7.3

* [Doc] 1st round copyediting, 7, 7.1, 7.2, and 7.3, removing EN parts.

* [Doc] 2nd round copyediting.

* [Doc] 3rd round copyediting.

* [Doc] Copyedit with reviewers' comments.
Co-authored-by: Mufei Li <mufeili1996@gmail.com>

* distributed APIs.

* add guide.

* add index.