docs: conflicting documentation of default value for `POWERPIPE_LISTEN`

[lucascherzer]

Describe the bug
The online docs at https://powerpipe.io/docs/run/server state, that the default value for POWERPIPE_LISTEN is network:

By default, Powerpipe will listen on all network interfaces, but you can pass --listen local if you only want to listen on the loopback addresses:

The CLI app states the opposite:

$ powerpipe server -h
[...]
--listen string           Accept connections from local (localhost only) or network (all interfaces / IP addresses) (default "local")

Powerpipe version (powerpipe -v)
Powerpipe v1.2.7

Expected behavior
The default values presented in online docs and CLI docs differ, the CLI seems to be correct. Please update the online docs to reflect that

[pskrbasu]

Thank you for bringing this to our attention, @lucascherzer. We will get the docs sorted.