"host" is repeatedly used as questionable descriptor for full url aka "http://localhost:8086"

_Describe the issue here._

complicated description arising from backup error here:
https://github.com/influxdata/influxdb/issues/25460

simple root cause:
`influx ping --host localhost` does not work
`influx ping --host "http://localhost:8086"` works

I'd consider it as an documentation issue.
There are loads of web articles from people trapped by this.
"host" in my mental dictionary is just the "host" part of an URL, while in influx world, obviously it refers to a complete url:
"protocol://host:port"

I know that any influx pro is just rofl on this case.
But climbing up the learning curve this are silly issues costing you hours of work.

##### Relevant URLs
- https://docs.influxdata.com/influxdb/v2/admin/backup-restore/backup/
- _Provide other relevant URLs (project issues, community threads, etc.)_

Start with the backup documentation URL and compare its use of `--host` with the related InfluxDB issue 25460. Identify where the expected full `protocol://host:port` URL is described; done means the relevant documentation clearly distinguishes the host value from a complete URL.

Written by the indexing model from the issue text.