F001 tempalte fixed, typo fixed

Description

F001 template fixed for the case when standby server exists in list, but no data for it. Typo in checks fixed

Related issue

https://gitlab.com/postgres-ai-team/postgres-checkup/issues/279

Examples

https://gist.github.com/dmius/7c91affdccbe8f63633b2a33fbd3be8d

Closes #279 (closed)