TD-1174: jdbc without host ip

fix two case of 'unexpected generic error in RPC'

Master

fix td-1189

[TD-1048]

Update cluster-ch.md

Update administrator-ch.md

Update insert-ch.md

Update Model-ch.md

Update faq-ch.md

log an error message if failed to call `gethostname`.
don't update epset if peer returns empty epset.

Merge pull request #3182 from taosdata/feature/sangshuduo/add-a-badge-to-indicate-docker-pull-number

add a badge to indicate docker image pull number.

[TECO-7]

Update cluster-ch.md

Update cluster-ch.md

[fix bug]

[fix bug]

Feature/os

TD-1184 add error code

Master

Fmaster/lihui