[docs] fixing max_depth param description

[KOLANICH]

https://github.com/Microsoft/LightGBM/blob/59f10453dc4a3841339702524124063fa5db6870/src/treelearner/serial_tree_learner.cpp#L351

BTW, should it be unsigned?

[StrikerRUS]

@KOLANICH Thanks for your contribution!

Please follow this procedure to update parameter description.

[KOLANICH]

BTW, why not to do it on CI automatically?

[StrikerRUS]

Because after generating anything on CI side it should be pushed back to GitHub.

[KOLANICH]

Because after generating anything on CI side it should be pushed back to GitHub.

1. What's the problem with it? Azure Pipelines support secret variables.
2. If the docs are generated from the source, why not to remove them completely from the repo?

[StrikerRUS]

1. What's the problem with it? Azure Pipelines support secret variables.

It's still insecure. Also, It produces additional mess in the repo. Imagine: every commit is duplicated by the CI.

2. If the docs are generated from the source,

Only params description is generated from the source.

[StrikerRUS]

@KOLANICH Remembering your position about the CLA #1873 (comment), we are taking over your PRs, if you don't mind.

so feel free to close the PR and add the links and everything else you feel needed yourself from your account and your name, I don't object, …

Can you please clarify your comment?
#1879 (comment)

https://github.com/Microsoft/LightGBM/blob/59f10453dc4a3841339702524124063fa5db6870/src/treelearner/serial_tree_learner.cpp#L351
BTW, should it be unsigned?

[KOLANICH]

I just wonder why a signed int is used for a parameter which semantics is to be a number >= 0. Shouldn't an unsigned int be used for that?

[StrikerRUS]

Ah, got it, thanks!
But users can pass a negative value, e.g. -1 to indicate "no limit".

[KOLANICH]

But users can pass a negative value, e.g. -1 to indicate "no limit".

But 0 is also "no limit".

[StrikerRUS]

You are right!
It's possible to save all semantics with unsigned value. However, this change will be not backward compatible.

BTW, at present, all params are signed values, even num_boost_round and other which should be strictly greater zero.

[StrikerRUS]

Proposed changes were made in #2155.