LightGBM

[ci] fix check-docs error with AMD support website (fixes #3529) (#3530)

* [ci] fix check-docs error with AMD suppoort website (fixes #3529)

* only check docs

* browser user agent

* ignore AMD in CI

* better config

* better user-agent

* verify

* just drop AMD link

* restore CI

* empty commit

* empty commit

* just use linkchecker