[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

docs/.linkcheckerrc

@@ -6,6 +6,7 @@ sslverify=0
 [filtering]
 ignore=
   pythonapi/lightgbm\..*\.html.*
+  http.*amd.com/.*
 ignorewarnings=http-robots-denied,https-certificate-error
 checkextern=1